Search for Naya Rivera continues: Authorities use sonar to navigate murky waters

Authorities have shared the methods by which they are searching for actress Naya Rivera, best known for her role as Santana Lopez on "Glee," who is presumed dead after disappearing from a rented boat on a lake in Southern California Wednesday.

The search for her body wrapped 8 p.m. local time Friday night, after it became to dangerous for divers, and resumed 6 a.m. Saturday. On Friday, due to murky waters, police switched search tactics and began using technology to search for Rivera including sonar. According to the Ventura County Sheriff's Office, no remains have been found yet.

Police shared footage of the remotely operated underwater vehicle (ROV) on Twitter Friday, which they used to navigate Lake Piru's low-visibility depths.

"Here’s the ROV used by @TulareSheriff in the search for Naya Rivera at Lake Piru today," Ventura Co. Sheriff wrote. "This is one of many resources being used, along with side scan sonar, dogs, and divers."

The 37-second video shows the ROV being dropped into the water by a cord.

The lake bed beneath the water has almost no visibility, which meant human divers had to basically search by feel. The side-scan sonar allows crews to target, and search for, objects with a specific size profile, Ventura County Sheriff's Sgt. Kevin Donoghue, a spokesman for the agency.

Authorities also shared a video clip of the footage procured by the ROV at 30 feet deep to illustrate the water's cloudiness.

"Here’s an example of the underwater visibility at a 30-foot depth in Lake Piru," Ventura Co. Sheriff wrote.

In the video, they point to a tree, which is partially visible in the water.

Investigators believe Rivera drowned in what appears to be a tragic accident, according to a statement released Thursday by Ventura County Sheriff's Office Capt. Eric Buschow.

“We don’t know if she’s going to be found five minutes from now or five days from now,” Buschow said at a news conference Friday.

Rivera’s son told investigators that he and his mother had been swimming in the lake, and he got back in the boat, but Rivera did not, according to Buschow. The child is in the company of family.

"The interview with her son was key," said Donoghue. "We received enough specific details from him to lead us to conclude that she disappeared in the water and did not come back."

That's why the search effort is now entirely in the water, he said. Authorities are not releasing additional details about their interview with the boy out of respect for the family, he said.

Sheriff's officials investigating the incident say there was no evidence of foul play or any indication of a suicide. The death appears to be the result of an accident of some sort.

Search still on: For 'Glee' star Naya Rivera, believed to have drowned in a tragic accident

Contributing: Andrea Mandell, Hannah Yasharoff, USA TODAY, Gretchen Wenner, Jeremy Childs, Ventura County Star

This article originally appeared on USA TODAY: Naya Rivera: Search for 'Glee' star continues in Lake Piru with sonar