The Interstate 35W Bridge Collapse
Written by Sergeant Steve Labatt   

WHEN THE SUN CRESTED the riverbank August 2, 2007, it illuminated the twisted green girders, box beams, rebar, and crushed concrete of the I-35W bridge collapse. The largest crime scene ever processed by the Hennepin County Sheriff’s Crime Lab Unit lay waiting.

The planning and staging of equipment to document the disaster began in the predawn hours as the Sheriff’s Crime Lab mobilized the Hennepin County Sheriff’s Major Crime Scene Unit, the Sokkia forensic-mapping equipment, digital cameras, and personnel. At the same time, the unit coordinated with the Hennepin County Medical Examiner’s Office for victim recovery and established a partnership with the Minnesota State Patrol and the Minneapolis Police Department for the documentation of the entire bridge collapse, both on land and in the water.

This overnight planning meant that soon after sunrise everyone involved in the recovery and documentation efforts had a clear understanding of their duties and responsibilities. The Hennepin County Sheriff’s Office Crime Lab was responsible for the documentation of all vehicles and victims recovered from the Mississippi River. Meanwhile, the Minnesota State Patrol would document the vehicles in the collapse area on land and on the bridge deck above the water.

Both agencies utilize the same forensic mapping equipment to document crime scenes and accident scenes. This was a valuable asset because the two agencies were able to shoot the same control points throughout the scene and then merge their data with the FBI Evidence Response Team’s data for one complete map of the entire collapse.

The Sheriff’s Crime Lab Unit, the Sheriff’s Detective Unit, the Hennepin County Medical Examiner’s Office, and the Minneapolis Police Department then set up protocols for vehicles that were located and removed from the Mississippi River with victims inside. It was important that all vehicles located and removed from the river were handled exactly the same way. The Crime Lab Unit conducted pre-dive meetings with the law-enforcement divers to give specific instructions on what to record during the dive, including:

  1. Position, direction, description, and license plate of the vehicle;
  2. Condition of the windows;
  3. If a victim was located in the vehicle, document their position inside the vehicle and whether they were secured by a seat belt;
  4. Depth of the water; and
  5. If the diver had to break out any windows, which window was broken.

Divers then tied a buoy to either the driver or passenger side-view mirror to locate the vehicle from the surface.
By nightfall on August 2, 100 feet of the area downstream from the collapse had been searched bank-to-bank using local law-enforcement divers. On August 3, recovery operations moved to the area upstream of the collapse.

Prior to beginning the upstream recovery efforts, the Hennepin County Sheriff’s Water Patrol Unit located several targets in the upstream area with side-scan sonar. Local law-enforcement divers then used systematic search patterns to confirm the vehicle locations.

The protocols established through the pre-dive meetings proved invaluable as divers communicated the information to the teams on the surface. The information was then relayed to the command post to be compared with information that was known about the possible victims.

As the sun set on August 5, 75 feet of the river upstream of the collapse had been searched and seven vehicles had been located in that area. Drivers and passengers belonging to six of those vehicles were located in area hospitals, but the seventh driver was still missing. Local law-enforcement divers removed this vehicle—a minivan—with the assistance of the United States Army Corps of Engineers.

More valuable resources added to a multi-agency effort


On Saturday, August 4, President George W. Bush visited the bridge-collapse site and met with area leaders including Hennepin County Sheriff Rich Stanek. At that point, local law-enforcement divers had searched the dark, murky waters of the Mississippi River for days, and had reached the limits of their existing resources. The twisted rebar, metal girders, concrete, and river current under the surface of the Mississippi River were creating the danger of entanglement. Later that Saturday, they received the help they were hoping for: federal resources were on the way to assist in the recovery.

A crane and other heavy equipment were used to move heavy chunks of concrete and metal from the river onto barges nearby. Clearing the debris was necessary to allow divers the access they needed to recover many of the victims.

The help arrived quickly. U.S. Army Defense Coordinating Officer Colonel Michael Chesney and U.S. Navy Mobile Diving and Salvage Unit Two Com-mander Daniel Shultz arrived the next day. Then, on the evening of Monday, August 6, the Hennepin County Sheriff’s Office escorted four semi-tractor trailers followed by vans filled with members of the U.S. Navy Mobile Diving and Salvage Unit Two (MDSU2) from the Minneapolis/St. Paul International airport to the lower lock at St. Anthony Falls on the Mississippi River. By 2 a.m. on August 7, the U.S. Navy MDSU2 divers began river operations, verifying the upstream searches by local law-enforcement divers, accounting for all vehicles, and confirming that victims were not located in those vehicles.

With the outside areas searched, the U.S. Navy divers then began the dangerous job of looking for victims and vehicles under the bridge. During this search, U.S Navy divers located several items of personal property floating among the debris and on the bottom of the riverbed. The Sheriff’s Crime Lab and the Minneapolis Police Department coordinated collection of the property.

Carefully following protocol to recover the victims

On the morning of August 9, U.S. Navy divers located several vehicles in the collapse area near the right descending bank. The discovery of these vehicles brought news that would finally provide closure for a family after nine long days: The divers had found the first of the eight known missing victims. He was located outside of his vehicle and partially inside another vehicle.

Locating and recovering this victim was the first test of the protocols that were established during the meetings and daily briefings. All victims would be placed in body bags underwater where they were recovered to avoid exposure to the media and crowds who gathered on nearby bridges and buildings for the entire 20-day recovery. Investigators from the Medical Examiner’s Office were onsite along the left descending bank and Medical Examiner Dr. Andrew Baker observed from the recovery watercraft.

With all personnel in place, the U.S. Navy divers walked the victim along the bottom of the river, and at 12:30 p.m. the victim was brought to the surface and transferred to the recovery watercraft. With a crackle over the radio, River Command made an announcement to all personnel on the river operations that a victim had been recovered from the river. All personnel observed a moment of silence for the victim and his family. The victim was then brought to the left descending bank where investigators from the Sheriff’s Crime Lab and Detective Unit, Hennepin County Medical Examiner’s Office, Minnesota State Patrol, and Minneapolis Police conducted their investigation behind the concealment of a large tent.

This same protocol would be repeated approximately 1.5 hours later when U.S. Navy divers located an SUV that was included on the list of missing vehicles. In the SUV, they found the second missing victim secured in a car seat in the back seat, and the third victim was found in the driver’s seat. Informa-tion about the missing, previously given at the daily briefings, was consistent with what the divers located. The extrication went flawlessly by the U.S. Navy divers. Then, the U.S. Navy divers relayed the critical information about the position of the car seat in the vehicle, restraint straps, and their condition to investigators on the dive platform. The victim was brought to the surface, transferred to the boat, and then transported to the left descending bank where the established protocols would be followed once again.

Utilizing DNA to identify victims’ remains

Due to the amount of bridge debris and damage to the vehicle, the recovery of the third victim was difficult. The U.S. Navy divers had to use hydraulic cutters, saws, and spreaders to perform the extrication. It was not until the early morning of August 10 that the victim was recovered. The discovery of the second and third victims also set into motion another set of protocols that had been established: the identification of the human remains through DNA.

The Sheriff’s Crime Lab Biology Section and Hennepin County’s Medical Examiner’s Office had a coordinated approach to ensure timely DNA identification results. In some cases, religious traditions of a victim’s family require swift identification so funeral services can take place within a specific timeframe. Due to prolonged submergence and lack of dental records, DNA identification was the only option to positively identify some of the victims. Upon receiving samples from both victims on the afternoon of August 10, Crime Lab forensic scientists and DNA analysts worked through the weekend and made positive identifications within approximately 48 hours.

A complicated, shifting, multi-layered crime scene

One of the greatest assets of this team effort was the intelligence and photo-graphs provided by NAVSEA (Naval Sea Command Systems). After each of their six-hour dives, divers provided to their command detailed information about the environment in the water and the relative position of the vehicles. Some vehicles lay on top of each other and one was upside down. Receiving detailed photographs and drawings of the layout of the vehicles gave the Sheriff’s Crime Lab Forensic Mapping Team the needed information to complete this portion of the final mapping.

The Hennepin County Sheriff’s Office used this aerial photo—taken by the Minnesota Department of Transportation—along with the intelligence provided by the U.S. Navy divers to mark the position, direction, and location of the vehicles. This picture gave investigators a representation of the jumbled conditions below.

 

A severe overnight storm on August 11 caused extensive damage to the River Command area and the U.S. Navy dive platform. It also destroyed the body-recovery post at the river’s edge. All areas were cleaned up and reestablished by mid-morning, but the associated storm surge increased the river current to seven knots, causing the U.S. Navy to suspend dive operations.

Once freed from the tangle of debris underwater, recovered vehicles with victims still inside were lifted partially out of the water, covered with a large tarp, then placed on a nearby barge. The vehicles were then transported to the riverbank, loaded onto a flatbed tow truck, and hauled to a secured impound lot where the victims could be extricated after additional photographs were taken to document damage, position of the gear shift, ignition position, and position of the victims. A similar documentation process was carefully carried out for unoccupied vehicles, as well.

Meanwhile, the U.S. Army Corps of Engineers forecasted that the water level of the river would increase by two feet within 24 hours. Hennepin County Sheriff’s Office command staff, U.S. Navy commanders, and the U.S. Army Corps of Engineers knew they needed to control the river flow. Within hours, the U.S. Army Corps of Engineers developed a plan to control the 13 miles of river flow between the Coon Rapids Dam and the Upper Lock at St. Anthony Falls. This allowed the Mississippi River to be lowered up to five feet between the Upper and Lower Lock at St. Anthony Falls, giving the U.S. Navy divers 10 hours of dive time that they would not have had otherwise.

That 10-hour period proved to be very successful. In a methodical search of the debris field along the right descending bank, U.S. Navy divers located three additional vehicles crushed under concrete and steel. Now, they just needed help gaining access to the vehicles. Over the next few days, equipment operators from St. Paul-based contractor Carl Bolander & Sons Co. removed large pieces of concrete and metal to help clear the way to those vehicles and victims.

In the late afternoon of August 15, the SUV driven by one of the previously recovered victims was removed from the river, revealing another SUV. Divers searched the newly discovered vehicle and found two victims inside, but even the extensive work underwater to remove both of them was unsuccessful.

The previously established protocol for the removal of vehicles with victims still inside was quickly set into motion, including the notification of the Henne-pin County Medical Examiner’s Office. U.S. Navy divers attached straps to the SUV’s undercarriage and the vehicle was raised to the surface. The vehicle was quickly covered with a large tarp to shield it from the view of the on-looking media and crowds before it was raised completely out of the water and placed on the barge. The barge was piloted to the left descending bank where it was off-loaded onto a flatbed tow truck. From there, the Sheriff’s Office and Minneapolis Police escorted the tow truck to the impound lot for extrication of the victims.

In a secure area, out of view from the media and the public, the delicate process of removing the fourth and fifth missing victims began. The Minn-eapolis Fire Department used hydraulic cutting tools to cut open the vehicle and allow access to the victims. When the bodies were freed, the Sheriff’s Office Crime Lab took photographs to document the process as the Medical Examiner’s Office removed the victims.

The Hennepin County Sheriff’s Office is the largest sheriff’s office in the State of Minnesota—but when the I-35W bridge collapsed on August 1, 2007, the agency faced a crime scene unlike any other. At the time of the collapse, 107 vehicles were driving across the bridge. The collapse killed 13 people and injured 98. In a remarkable team effort, 104 local, state, county, and federal public-safety agencies responded to the disaster.

Dive operations continued through the evening of August 15. Shortly after midnight, the U.S. Navy divers secured access to a midsize SUV that belonged to another missing person. Unable to remove the victim’s body underwater, the process to lift the vehicle began—but it was not easy. Attempts to remove the SUV from the debris caused the shifting of additional concrete and metal, so heavy-equipment operators had to remove large chunks of debris to allow the U.S. Navy divers a more secure connection to the vehicle. Soon after, the vehicle was pulled free of the debris and raised to the surface. The sixth missing bridge-collapse victim was removed from the vehicle at the impound lot by the Minneapolis Fire Department with the assistance of the Sheriff’s Crime Lab and the Medical Examiner’s Office.

To clear the way for divers, additional debris was removed from the river over the next few days. At the same time, cranes lifted the vehicles off of the collapsed bridge deck that stretched across the Mississippi River and pulled partially submerged construction vehicles out of the river. After the removals were completed, divers focused on the area where the construction vehicles once were, quickly locating a Bobcat skid-steer loader. A missing construction worker was reported to have been operating this loader at the time of the collapse. Divers made a thorough examination of the loader, but the construction worker was no longer inside.

After a large amount of debris had been removed from the river, Navy divers entered the river in the early morning hours of August 19, locating the last known car they were looking for with the seventh missing bridge collapse victim inside. The location of the car on the downstream side of the collapse area made it necessary to adjust established protocols. With the vehicle located farther downstream on the opposite side of the collapsed bridge, the contractor’s crane was used to remove the vehicle. Divers attached the lift straps to the car. The crane then lifted it from the river and onto the barge. The ropes were then cut and the tarp was quickly cinched up and tied.

Within just minutes, the barge was heading downstream. Meanwhile, all of the land-based personnel, including the Medical Examiner, were relocated to another area downstream along the Mississippi River called the Bohemian Flats. When the car arrived, a crane lifted it from the barge and placed it on the flatbed tow truck. The victim was extricated from the car one hour later at the private and secure area in the impound lot.

Debris removal continued throughout the day on August 20. Because of the large amount of debris, Sheriff’s Office Crime Lab personnel were staged on the barges to examine all of it for evidence as it was loaded onto the barge.

Finally, at 6:05 p.m. on August 20, divers recovered the final missing victim of the I-35W bridge collapse. The recovery of the eighth victim ended the longest, most intensive crime-scene investigation ever undertaken by the Hennepin County Sheriff’s Crime Lab.
A sense of accomplishment and calm settled over the riverbanks. We had completed our mission to reunite all of the known victims of the I-35W bridge collapse with their families.

 


ORIGINALLY PUBLISHED:
"The I-35W Bridge Collapse," written by Sergeant Steve Labatt
March-April 2008 (Volume 6, Number 2)
Evidence Technology Magazine
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