MANKATO, MN - For years, they have been used to find fish.  Now law enforcement across the country use them to find bodies in lakes and rivers.
Investigator Marc Chadderdon with the Nicollet County Sheriff's Office, said: "The Humminbird side scan sonar has been found to be the best device, so [for]  most agencies, that is what they purchased.  But there's a lot of settings and things that can be changed to manipulate to help us recover individuals."

62 officers from 27 different agencies in Minnesota and Iowa came out to Lake Washington to learn how to use this technology effectively.

"Today, it's a day out on the water.  We've submerged 3, chicken wire framed bodies, which we put in the water and give scenarios for the officers then to try and go out and locate and it will help us recover victims of drownings." Chadderdon explained.

The training is being done by Team Watters Sonar.  This couple travels the country helping first responders fine-tune their sonar equipment and even assist in search and recovery operations.  The duo has recovered 92 bodies since 2005 and in one case, found a body within 30 seconds of turning on the sonar.
Dennis Watters, of Team Watters Sonar, said:  "If we can come up here and help these guys go out and get it done in 15-20 minutes versus 3 or 4 or 5 days, then that's what it's all about."