An X-ray technician in South Carolina has solved his second unsolved case in recent months by using his knowledge to build a homemade sonar device that can see underwater.

In six months, four families have received answers to a question that has been lingering for years: Where is our missing loved one? The answers came with the help of a Myrtle Beach man and his boogie board.

In June, Jason Souhrada made headlines after using his sonar device to find a car with three missing men inside at the bottom of a North Carolina creek, closing a 40-year-old unsolved case.

Since then, he has used his free time to search the waters along the Grand Strand, where he found another car.

“We took her to the nearest boat launch, which was down here on Bay Road and Enterprise,” Souhrada said. “There was a launch down there. I just put it in the water, I wanted to be productive with it, so I went and searched the area, and sure enough, there was a car in the water.”

The car turned out to be stolen, but it inspired him to search for missing people in the area. During his search, he came across Daniel Riggs.

“I called my diver friend Adam Brown of Adam Brown Adventures in Columbia to ask if he wanted to come down and dive because I had done some research and found out about the Daniel Riggs case,” Souhrada said.

According to investigators with the Mount Pleasant Police Department, Riggs was last seen on November 9, 2015, when he purchased a quart of oil at a Food Lion in Myrtle Beach.

According to a police report, Riggs told his girlfriend he was in Georgetown, and investigators confirmed his cellphone was last located in that area.

“We decided to follow those phone signals and go back to the Georgetown dock,” Souhrada said. “We went into the water there and immediately found several vehicles. I think there were almost 25 total, if not more, within a quarter mile of the boat dock. We decided to send down an underwater drone that Adam had to expedite the search for the vehicle we were looking for, Daniel Riggs’ Dodge Nitro. The third vehicle we investigated turned out to be Daniel’s vehicle, so Adam dove in, took down the license plate number and we contacted police.”

Human remains were found inside the Nitro, but authorities have not yet confirmed that the remains found inside the vehicle are Riggs.

Souhrada and Brown both described their work as bittersweet.

“There’s so much water that needs to be checked, and the reality is it’s not always possible,” Brown said. “So private teams like us come. We don’t charge the families anything, you know. We just come on our own dime, on our own time, and we just try to do whatever we can to help.”

“The only reason I started doing this was because I saw other people doing it on YouTube and I wanted to have that same feeling,” Souhrada said. “I wanted to be able to help.”

Souhrada has advice for anyone looking for a missing person.

“It’s really important that family members keep searching and writing news stories about their missing loved ones because that goes a long way in keeping the story fresh. When people like me or Adam or another search team go out searching and see a car in the water, they wonder if that could be the missing man,” Souhrada said.