FBI’s Underwater Search and Evidence Response Team (USERT)

Part 3: On the Job

Imagine being immersed underwater. The water is thick and muddy. Your suit is keeping you dry, but the frigid temperatures are making your fingers numb. All you can see is darkness.

This is a real-life scenario for divers who are part of the FBI’s Underwater Search and Evidence Response Team (USERT). They must be able to conduct underwater searches in all kinds of conditions, often regardless of visibility, temperature, and pollution. Proper diving gear and attire, as well as collaboration with other teams, are key for diver safety, and underwater search tools and evidence collection protocol help ensure successful search and recovery operations. 

Gearing Up for a Dive 

USERT divers wear specialized gear to help them maneuver underwater and to keep open lines of communication with their colleagues on the surface during an operation.  

“We typically dive with full-face masks, which allow two-way communication between team members above and below the surface,” said Supervisory Special Agent and USERT Program Manager Brain Hudson. For additional insulation as well as head protection when overhead obstacles are present, divers wear steel Kirby Morgan Superlite 77 helmets, which weigh over 30 pounds on land. 

Waterproof dry suits are designed to keep the divers warm in cold water and protect against pollution and other unpleasant water conditions that could present health and safety risks. The suits usually cover the head, body, and feet. “We try to keep as much dirty water off the divers as we can,” said Hudson. “Your dry suit and full-face mask or helmet will keep you protected, so really, the only part—hopefully—that’s going to get wet is your hands.” 

When diving in icy conditions, divers wear additional dry suit layers for warmth. However, keeping the head and hands warm is the biggest challenge. “If it’s cold water or ice diving, you’re still going to lose your hand dexterity over time,” said Hudson. “There’s only so much you can do to keep your hands warm, even with additional dry gloves. Your head also gets cold.” 

On land, the FBI’s Technical Hazardous Response Unit (THRU) helps USERT set up ZUMRO tents (air-inflatable shelter systems) with heaters to give divers a place to dress and warm up after a dive. “We also keep several turkey fryers going with warm water so divers can dip their arms in there and pour on gear to keep the gear from freezing on the surface,” said Hudson.

In contrast, when it’s warm, USERT and THRU set up shade tents to help keep the divers cool, ensuring there is plenty of drinking water available to maintain hydration as well as electrolyte packets to mix in for extra sustenance.  

About This Series
This is the third and final part of a series giving you an inside look at USERT—from their rigorous training to tools of the trade.

Safety Measures: Collaborating with the FBI’s Technical Hazardous Response Unit (THRU) and Operational Medicine Program

USERT relies on collaboration with other teams to ensure efficient and safe dives. As a result, there have been no serious injuries to USERT divers thus far.

“One of our great benefits of USERT is that we work really close with THRU and the Operational Medicine Program within the Bureau,” said Hudson. “We have paramedics in the field who have gotten special training in dive medicine. They are DMTs, or dive medicine technicians, which is an extra-level certification. When we deploy on missions and trainings, we always have one or two medical staff who specifically specialize in dive accidents and medicine.”

In addition to medical support, THRU helps USERT with operational tasks, including setting up auxiliary equipment and resources, like setting up heating tents for ice dives or clearing heavy underbrush to pave the way to the water’s edge. 

Underwater Obstacles 

Beneath the surface, divers must be aware of potential challenges that could arise while on the job.

Decompression sickness is a risk in both recreation and in search and recovery diving—during a rapid transition from a high- to low-pressure environment, gas bubbles in the body form and may cause joint pain, difficulty breathing, chest pain, paralysis, and confusion. The consequences could be fatal.

To mitigate this risk, divers follow protocols and schedules created by the U.S. Navy that designate how long divers can stay underwater at certain depths and control their ascent rate up to the water’s surface. Divers also conduct all dives with at least one dive medical technician and paramedic present.  

USERT diver in like with gator

Sometimes divers meet other animals in the water—like this alligator, who made an appearance during a search in Big Cypress Indian Reservation in Florida.

Other potential dangers include entanglements that can trap or injure divers.

“Our divers have to contend with all sorts of underwater environments—for example, fallen or sunken trees or tall underwater vegetation, as well as man-made items like fishing line, razor wire, trash, and other items that end up in the water,” said Hudson.

“We attempt to mitigate these hazards in a couple of ways. All divers carry multiple cutting devices, so that they can attempt to free themselves. Our teams will periodically conduct entanglement training. In the event that they cannot free themselves or if other issues arise, our divers typically dive with surface-supplied air and communication devices so they can notify the dive supervisor, and we can send another diver to assist. This also means they won’t run out of air if they’re stuck underwater.” 

Sometimes divers also encounter animals that aren’t necessarily easy to swim with. “Our Florida team frequently deals with gators,” said Hudson. “We also did a dive in Alaska where we had to scrub the leaches off of the dry suits that the divers picked up underwater.” 

Top: USERT divers typically wear AGA full face masks, as shown, which allow them to listen and talk to teammates while underwater. Left: A USERT diver emerging from freezing waters in Burlington, Vermont.

Collecting Evidence 

USERT divers search for and recover items as small as shell casings and as big as shipwrecks. “We have a lot of tools in the toolbox—it really depends on what we’re looking for and what’s the best tool to find that,” said Hudson.  

“Our first divers in the water are typically going to give a report of what the bottom surface is like,” said Hudson. “Is it hard-packed, or is it very silty? When our first diver gets down and puts their hand in the mud, how far can it extend before hitting a stopping point? Is the mud up to your fingertips, up to your elbows? These types of conditions are taken into consideration when we do our searches, so we know how much we need to dig.” 

Despite the usual pitch-black environment they work in, divers rarely use lights below the surface because particulate matter churned up from walking on the bottom diffuses any light. Instead, divers often rely on intelligence gathered during the initial dive, as well as metal detectors and sonar equipment—usually controlled from the surface—to locate and direct them toward evidence and other items they’re searching for.

Sonar, short for “sound navigation and ranging,” is a technique that uses sound waves to locate objects. It is useful for exploring and mapping bodies of water because sound waves travel farther in the water than radar and light waves. “As items go up in size, the areas that need to be searched get bigger, and the initial intelligence about the site may not be quite as concise,” said Hudson, who explained that sonar systems are especially useful in these scenarios.  

USERT also uses remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs), which both collect images and other data underwater, as well as investigate areas that are too dangerous for divers.  

As divers find items to recover, they often place smaller objects in airtight containers and then carry them back up to the surface. 

But if items are over 15 pounds, divers use lift bags. Smaller lift bags look similar to parachute-shaped balloons that divers can inflate underwater and attach to the items that need to be raised to the surface. Divers can inflate these bags using either a regulator or a low-pressure inflator hose. This allows the diver to adjust the buoyancy of the lift bag and to safely control the ascent. Larger lift bags can raise objects as large and heavy as 2,000-pound vehicles.
Upon collecting all the items at the scene, USERT follows chain of custody guidelines. Each agency—whether the FBI or a local law enforcement department—follows its own rigorous processes. Most items are sent to a lab for further examination. Depending on the amount of time spent underwater, lab technicians can then gather information as detailed as cell phone data or DNA samples.  

USERT: Tools of the Trade

Peer into the Underwater Search and Evidence Response Team (USERT) toolbox to see how everyday items and specialized equipment help the team process a scene.

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