Investigating an Underwater Crime Scene

A prolonged drought lowered the water levels of Lake Mead, about 30 miles from Las Vegas, Nevada. Throughout 2022, people enjoying recreational activities on the lake began finding human remains. By the end of October, the remains of six individuals had emerged from their watery grave, at least one of them was dead from a gunshot wound, making it a homicide (Wolfe, 2022). There’s no way to tape off a crime scene in a lake or river, so how do the police go about investigating an underwater crime scene?

Image 1: Lake Mead
Credit: https://commons.wikimedia.org/wiki/File:Lake_Mead_National_Recreation_Area_LAME3643.jpg

History of Investigating an Underwater Crime Scene

When we consider that fingerprints were first used to solve a crime in 1892, Forensic Diving is a relatively new form of investigation. In the 40 years since police started using divers to recover evidence, recreational scuba diving has adapted to the needs of a police investigation. The former recreational divers had to make up their investigative techniques as they went along (Phillips, 2023).

Problem-solving in Underwater recovery.

On land, recovery teams are required to bag the hands of a body, in case evidence is located under the fingernails. But how could that action be performed underwater? A paper bag, routinely used on land is useless under water. Plastic bags filled with water, losing the evidence. Emergency Response Diving International (ERDI) came up with a solution. They double up knee-hi nylon stockings and use those to bag up the hands and retain evidence (Phillips, 2023).

Without proper training, divers would ‘snatch and grab’ rather than carefully document the location of potential human remains and evidence. The US Navy worked with Florida State University to establish standardized procedures in 2002. With their combined efforts, Underwater Crime Scene: A Guide for Law Enforcement was published. Using the methods in the manual reduces the amount of time divers spend in the water, making it safer, and increases the likelihood their efforts will be recognized in court (Florida State University).

Processing an Underwater Crime Scene

How does an investigative diver establish that the underwater location is a crime scene? Every underwater recovery operation has the chance to turn into a criminal investigation, therefore the procedures for evidence recovery must be used from the start.

What are forensic divers searching for?

There are three things that forensic divers are looking for. These are bodies, vehicles, and evidence.

Image 2: A submerged Vehicle
Credit: https://commons.wikimedia.org/wiki/File:Submerged_car_near_Morpeth_Dock,_Birkenhead.jpg

When seeking for bodies the searchers need to know how long the person has been missing. Using this time frame enables the team to take into account the Five Phases of Motion for a corpse in the water, which follow the standard stages of decomposition for a body (Coronertalk.com, 2016).

1. sinking to the bed
2. moving along the bed with the current of the water
3. rising to the surface due to bloating from decomposition
4. moving along the surface with the current of the water
5. sinking again, for the final time

With these in mind, searchers work out an area that is most likely location for a body.

Locating the area to search

The five phases of motion are one way to narrow down the search area. If the water is shallow enough, cadaver dogs can sometimes sniff out even an underwater corpse. Technology can help, sonar can be utilized to seek out underwater objects, including bodies. But they can only locate larger objects, so they cannot help in searching for human remains, such as bones, or evidence, like ropes or a gun.  Remotely operated underwater vehicles are useful in these searches as long as the limitations are considered. Images from an underwater vehicle can be an issue as the water distorts the images, such that they appear both closer to the vehicle and larger (Magni, 2023).

All of these methods take place without putting people at risk, but in the end, once the location area is narrowed, the divers must enter the water to perform a search.

How do the forensic divers perform the search?

Most people practice scuba diving in a clear, treated swimming pool. This leaves divers unprepared for open water that is dark, murky, and often polluted. Now imagine you are looking for crime scene clues in this gloom. The bed of the water body can be covered in sediment. The water itself can be polluted and contaminated, so it is no wonder that technology is used to concentrate the search on a smaller area. With limited visibility, divers can run their hands or feet onto glass or nails. And depending on the area, the local wildlife can be unfriendly. Fish and turtles can attack if disturbed.

Just as with a fingertip search on land, (https://mozartcultures.com/en/working-the-crime-scene-control-preserve-record-recover/ ) an underwater search must follow a strict pattern to ensure that all evidence is recovered. What it comes down to, is putting your hands in the grimy sediment and feeling about for clues. The divers work in pairs. Because of the low visibility, a rope is strung across the search area. The divers work one on each side of the rope, holding on so that the search pattern is scientific. They pat the mud, hoping to feel for evidence, as they can see nothing. Once the line is fully searched then the rope is moved a set distance and the job begins again (Morton, 2016). It is tiring work and requires extreme care. As mentioned above, any movement of the water, such as a diver swimming too vigorously, can move not only sediment but also human remains or evidence (Phillips, 2023).

How is evidence recovered from an Underwater Crime Scene?

A vehicle is in the water. The divers go down and establish that a body is inside. Before the vehicle can be towed out, the body should be removed to preserve the dignity of the deceased.

To recover a body from underwater, forensic divers have created a special body bag with mesh drainage patches. Much as the white tents on land exist to preserve the dignity of human remains, so do these body bags. No gawkers can see the deceased as the divers bring it to the surface. Any trace evidence on the body is also collected and preserved by the bag. As mentioned above in the problem-solving section, the hands, and potential evidence can be bagged with nylon stockings. All of this is vital if a crime is to be solved (Phillips, 2023).

Techniques for Investigating an Underwater crime scene

As mentioned above, the techniques for investigating an underwater crime scene in low and zero visibility mostly involve luck. The technological search methods, such as remote drones have limited use in the gloom. Sonar can help create a 3-D map of the bed of the lake or river, but eventually, the divers have to enter the water. A number of the techniques cross over from underwater archaeology (Magni, 2023).

Image 3: Underwater Archaeology
Credit: https://commons.wikimedia.org/wiki/File:Scale_drawing_underwater.jpg

Both sciences require detailed information as to the location of found artifacts.

Is it possible to tell if the death was accidental or a homicide?

In the Lake Mead case, we started with, one of the skulls still showed signs of bullet trauma, but what about the others?

After a body is removed from the water, an autopsy is carried out. If the death is recent, then a frothy liquid in the lungs or other lung damage can suggest the person drowned, rather than being a dead body disposed of in a lake. Water in the stomach is also suggestive of drowning.

The cause of death is more difficult to determine if only remains such as bones are found. Diatoms, tiny creatures that live in water can be found in some organs and bones if the person drowned. Often, the cause of death cannot be determined without the existence of visible trauma wounds on the bones (Magni, 2023).

Conclusion

Although forensic diving for investigating an underwater crime scene is relatively new, the specialists call upon their training in recreational scuba diving to help them. They have built up techniques from archaeology and by trial and error. Guidelines are now established to ensure that any evidence found is admissible in a Court of Law.

References

Wolfe, E. and Musa A., (2022) More Human Remains Found in Lake Mead, marking at least the 6^th Discovery this Year. ABC Eyewitness News. October 28. https://abc7chicago.com/bodies-lake-mead-human-remains-found-water/12386656/

Phillips, N. (2023) Trace Evidence Preservation During Underwater Body Recovery. ERDI Blog.  https://www.tdisdi.com/erdi-news/underwater-trace-evidence-preservation/

Florida State University. Underwater Crime Scene Investigation: A Guide for Law Enforcement. AUTM Better World Project.  https://autm.net/cmswebparts/custom/bwp/generatePDF.aspx?story=%2FAbout-Tech-Transfer%2FBetter-World-Project%2FBWP-Stories%2FUnderwater-Crime-Scene-Investigation-A-Guide-for-L

Coronertalk.com (2016) Underwater Crime Scenes. Coroner Talk Podcast. https://coronertalk.com/underwater-crime-scenes

Magni, PA., Guareschi, E., and Paba, R. (2023) Forensics are Different when Someone Dies in a Body of Water. First You Need to Locate Them. The Conversation. May 18. https://theconversation.com/forensics-are-different-when-someone-dies-in-a-body-of-water-first-you-need-to-locate-them-204921

Morton, E. (2016) What’s it like to be an Underwater Crime Scene Investigator? Atlas Obscura. July 22. https://www.atlasobscura.com/articles/what-its-like-to-be-an-underwater-crime-scene-investigator