Karen Moore went missing from her South Florida home on eve of her 53rd birthday. The nurse was scheduled to pick up her 8-year-old daughter from Girl Scouts camp, but didn't show after missing her shift earlier that day, June 27, 2001.

She and her white 1999 Saturn car were never seen again – until a year ago.

Sunshine State Sonar founder Mike Sullivan was scanning a pond tucked away behind a strip mall in Davie, Florida, north of Miami, in January 2023. Footage from that day posted on YouTube shows a wheel slowly take shape on the sonar screen. Throwing a buoy down to mark the spot, Sullivan stays in the boat while YouTuber Britain Lockhart suits up and dives down to find Moore's white Saturn with human remains inside.

It may have been a major breakthrough in Moore's case, but finding a car wasn't surprising, really. Sullivan found more than 250 cars in Florida's many man-made canals, ponds and fountains in 2023.

By day, Sullivan owns an auto-parts ecommerce company. In his off-time, he offers his diving skills, sonar equipment and team of volunteers to any local official willing to give him any morsel of a clue that could help him chip away at the otherwise-stagnant list of cold missing persons cases.

In doing so, he also provides answers for families who have been missing their loved ones for years, sometimes decades.

"I'm happy to be able to have her home," said Christina Baber, Moore's daughter, in a recent interview with USA TODAY. "I lost my mom 22 years ago, almost, and it's a day I never thought would happen."

1,735 missing people in Florida's 7,500 lakes and 76,000 storm water ponds

Florida is covered in water. In addition to the 7,500 lakes and 12,000 miles of waterways, a 2020 survey cited by the University of Florida found a whopping 76,000 manmade ponds for storm water drainage in the state.

This means there are lots of places to look for clues for Florida's 1,735 missing persons cases.

Sullivan sifts through databases like the National Missing and Unidentified Persons System (NamUs), The Charley Project and Map the Missing, filtering out those who went missing with their car.

He has help sorting through the thousands of ponds where these cars could be hiding, the equivalent of Spider-Man's "guy in the chair." Her name is Shelly Ranae, and from her post in Virginia, she pores over satellite maps year by year, looking for bodies of water on routes the missing could have taken that have remained filled since the person was last seen.

These aren't always obvious. Many manmade ponds for storm drainage in Florida are more like glorified puddles, dotting major roadways and new housing developments. Sunshine State Sonar found Sandra Lemire's car, missing since 2012, under 14 feet of water that collected in the corner of a highway onramp near Disney World.

Once they get a hit for a car on his radar, Sullivan or one of the other volunteer divers he occasionally collaborates with suits up. They brave waters with sewage, litter and sometimes alligators to crawl the dirty depths in search of someone's loved one. He said he's located nearly a dozen bodies in submerged cars since starting in July 2021, and it is always those final moments before discovery that are most intense.

"My stress level was through the roof," Sullivan said in an interview with USA TODAY about diving on Lemire's car. "I had to sit down, catch my breath and just calm myself down before I got in that water...but you have to do it...like this is the end, we have to find out if this is her car or it's belonging to another case."

Miami-Dade waters hold dozens of stolen cars turned into 'artificial reef'

In the first week of 2024, Sunshine State Sonar located two cars with human remains. One appeared to have skeletonized remains of three people, Sullivan said, but officials have only confirmed one human body as of Thursday. The other car belonged to a missing person, Maureen Therese Sherman, and officials are testing the remains to see if they belong to her too.

Sullivan was on one of his expeditions down to the Miami-Dade area, where he estimates 1,000 cars are hiding below the waters' surfaces. (A spokesperson with the Miami-Dade Police Department told USA TODAY there is no way to know exactly how many submerged cars there are in the county, but admitted 1,000 was possible.)

Many of the cars are clearly stolen, Sullivan said, given away by a brick tied to the gas pedal or a plank rigged to the steering wheel to drive it into the pond unmanned. He said officials instruct him to leave those cars be, sparing the department's resources in favor of letting them become "artificial reef."

Sometimes, he has to sort through dozens of these cars to find one linked to a case. He said the canal where he found Sherman, missing since 1985 from her home nearby, had 24 cars in it.

While diving on another canal in the area the same weekend, Sullivan said they stopped counting at 17 cars. Other nearby "honey holes," as he calls them, can hold 30 cars, or more.

Even if a car he finds doesn't match a missing person profile Sullivan has in mind, he still tries to peek inside to see if there is evidence of a body. When he found a 1983 Oldsmobile in a mall pond, he shook the sediment that settled in the backseat, sending a shoe still attached to leg bones floating to the surface.

Sullivan said he wants to start branching out, scanning more retention ponds on the sides of the highway where people may have never thought to look.

Occasionally, people tell Sullivan not to look for their missing relative, hoping to avoid grieving them a second time if he finds their body. But he perseveres with the case anyways, believing that some loved one could still want answers.

"I feel kind of obligated to do this for (families)...I know if I don't do it, then they will never know because nobody else will do it," Sullivan said. "It's up to me, it's up to our team. If we can't do this, that family's never gonna get answers. And we carry that on our shoulders."

Baber held memorial service for found mother: 'Thank you for bringing closure to another family'

Baber said her mother's neighbor was the last to see her leaving her house the day before she didn't show up for work.

Moore was in the process of divorcing Baber's father when she went missing, and Baber said it was out of character for her not to show up for their scheduled visitation time.

"Everything was centered around my childhood happiness," Baber said about her mother, remembering their frequent visits to the children's museum and the zoo together. "I lost that rather quickly once she went missing."

Detective Eddy Velazquez from the Davie Police Department said the investigation into Moore's case is still open and ongoing. He confirmed the remains in the car belonged to her, and said it was not ruled a homicide.

Baber said she has never stopped trying to find answers about her mother–where she was going that night, who she was in touch with and how her car ended up in a pond far back from the roadway.

But with her mother's body found, Baber was able to hold a memorial service, with family flying in from as far as Alaska, she said. Baber's twin daughters Eliza and Olivia look at the picture of Moore next to her urn in Baber's home in Indiana, hearing stories about the grandmother they never met.

"I'm so thankful to finally have closure and have her home. It's still surreal at the same time. I mean, my whole life has been wondering what happened to my mom," she said.

Baber keeps in touch with Sullivan regularly, following along with his search and discoveries.

"Any time he has found anybody...I send him a text saying 'thank you for bringing closure to another family,'" she said, pausing as her voice trembled with emotion. "They don't have to go out and do what they're doing. And they are. It's such a wonderful thing."