Crime: Underwater Footage from Naya Rivera Search Released: She Could Be Found in '5 Minutes' or '5 Days'

‘Glee’ Actress Naya Rivera Presumed Dead; Recovery Tactics At Lake Shift – Update

  ‘Glee’ Actress Naya Rivera Presumed Dead; Recovery Tactics At Lake Shift – Update UPDATE, Saturday, 11 AM: The Ventura County Sheriffs Department is continuing its search today for Naya Rivera at Lake Piru. The murky and debris-strewn lake has made recovery efforts difficult for the search teams. The Tulare County Sheriffs and San Luis Obispo Sheriffs are also participating in the search for Rivera, who is presumed dead after diving off a boat into Lake Piru and never resurfacing.

The search for Naya Rivera at Lake Piru continues, two days after she disappeared during a boating trip with her son.

Naya Rivera wearing a pink dress © Vittorio Zunino Celotto/Getty Images Naya Rivera

Authorities searching for the missing Glee star released footage late Friday to show just what they are up against as they comb the lake's floor.

Ventura County Sheriff's Office released video obtained when they deployed a remotely operated vehicle (ROV) 30 feet from Lake Priu's surface during the search for the star's body.

The ROV was sent down to investigate a dark shape which turned out to be a tree branch. The footage shows just how low the visibility is.

WATCH: Police Give Update on Glee Star Naya Rivera's Disappearance After Finding Body in Lake

  WATCH: Police Give Update on Glee Star Naya Rivera's Disappearance After Finding Body in Lake Naya Rivera went missing on Wednesday during a boating trip at Lake Piru in Ventura County, California, with her 4-year-old sonOn Monday afternoon, police held news conference at Lake Piru in Ventura County, California, where the Glee star went missing last week. Watch the press conference live above.

During a press conference on Friday, authorities said that while sonar equipment has picked up several underwater images, none of the objects detected are Rivera.

"Unfortunately, they did not locate Naya Rivera. They are still searching," Ventura County Sheriff's Office Captain Eric Buschow told reporters, calling the situation a "difficult" one because "we don’t know if she’s going to be found five minutes from now or five days from now."

Naya Rivera 'Mustered Enough Energy' to Get Son on Boat but 'Not Enough to Save Herself': Police

  Naya Rivera 'Mustered Enough Energy' to Get Son on Boat but 'Not Enough to Save Herself': Police Naya Rivera's 4-year-old son Josey "told investigators that he looked back and saw her disappear under the surface of the water," Ventura County Sheriff Bill Ayub told reportersOn Monday, the former Glee star's body was found  five days after she went missing during a boating trip at Lake Piru in Ventura County, California, with her 4-year-old son, Josey, whom she shares with ex-husband Ryan Dorsey.

Lake Piru, which is located about 57 miles north of Los Angeles in Ventura County, California, is nearly two miles long and 130-feet deep at some points.

Buschow explained that responders are focusing on the north and eastern sides of the lake, and are using a side-scanning sonar to help focus the divers' search.

Ventura County Sheriff Sgt. Kevin Donoghue tells PEOPLE that the sonar device "paints pictures of the lake bed floor, and when it sees an anomaly, an object that's consistent with the shape and size of what we're looking for, then we send divers to search that specific area."

Naya Rivera standing next to a suitcase: CHRIS DELMAS/AFP via Getty Images Naya Rivera and son Josey © Provided by People CHRIS DELMAS/AFP via Getty Images Naya Rivera and son Josey

RELATED: Petition Created to Add Warning Signs to Lake Piru, Where Naya Rivera Went Missing

Given the size of the search area, this makes for a much more efficient and targeted investigation.

Donoghue tells PEOPLE that there are currently three sonar devices out on the water, and Buschow said that there are about 40 personnel involved in the search on Friday.

Demi Lovato Says She Will 'Forever Cherish' Playing Naya Rivera’s Girlfriend on Glee

  Demi Lovato Says She Will 'Forever Cherish' Playing Naya Rivera’s Girlfriend on Glee Demi Lovato appeared in the show's fifth season as Dani, who had a short-lived romantic relationship with Naya Rivera's Santana LopezThe "I Love Me" songstress, 27, is looking back on the time she spent as a guest star on Glee, sharing that she will "forever cherish" her role as Rivera's girlfriend on the hit FOX television series.

"We can’t predict" when she will be found, Buschow said at the press conference. "We may find her in an hour from now or several days from now. So there’s no way to predict that."

Rivera, 33, was presumed dead on Thursday, one day after her 4-year-old son Josey was found alone on a pontoon boat at Lake Piru, where they had been swimming.

Josey was deemed "in good health" and has been reunited with his dad and Rivera's ex-husband, Ryan Dorsey. The toddler told investigators that his mom never got back into the boat after they had been in the water, according to a press release from the Ventura County Sheriff's Office released Thursday.

Donoghue tells PEOPLE that while the events that led to Rivera's disappearance are "still a mystery," he adds that there is no reason to suspect foul play or that Rivera was attempting suicide.

RELATED VIDEO: Divers Search by Touch Underwater for Naya Rivera Due to Low Visibility: 'Kind of a Braille Search'

"I think at some point in time we will find her," Donoghue says. "I will say that we are hopeful to find her. We want to bring peace and closure to the Rivera family. This is a tragic event."

Naya Rivera’s Body Was Found Shortly After Glee Costars ‘Prayed for Her’ at Lake’s Edge: Police

  Naya Rivera’s Body Was Found Shortly After Glee Costars ‘Prayed for Her’ at Lake’s Edge: Police The former Glee star was reported missing on Wednesday following an outing to Lake Piru with her young son Heather Morris and other Glee cast members were seen gathered together at Lake Piru on Monday, just hours before Rivera's body was found. "Some of her cast members from Glee came to the lake and they were allowed to come down to the water's edge, and they, as a group, they prayed for her," Ventura County Sheriff’s Office Sgt. Kevin Donoghue tells PEOPLE.

"If we don't find any clues today, we'll still be out here tomorrow," he says.

As the search for the Glee star continued on Friday, poor visibility conditions at the lake made it difficult.

"The visibility is about one to two feet," volunteer diver Max O'Brien told reporters Friday. "... There's a lot of tree branches and overgrowth from when the lake was lower, so we're digging through, breaking through sticks and searching a heavy brush bottom."

"Under the water, it's a lot by feel," he said. "Again, there's a lot of shrubbery and sticks that we have to break through as we're going through, so it's kind of a Braille search."

Naya Rivera et al. posing for the camera: Gregg DeGuire/Getty Images Naya Rivera and son Josey © Provided by People Gregg DeGuire/Getty Images Naya Rivera and son Josey

RELATED: Naya Rivera Posted a Touching Photo with Her Son Days Before Disappearance: 'Just the Two of Us'

Donoghue said on Thursday that responders "don't know" if Rivera's body will be able to be recovered. "If the body is entangled in something underneath the water, it may never come up," he said.

Also on Thursday, the sheriff's office released CCTV footage of the lake's dock, which showed Rivera and Josey arriving, renting a boat, and launching northwards on the lake. The mother-son pair were alone, each with a backpack, and the actress also carried a large white sack.

Lake Piru is known for its dangerous conditions, and Donoghue previously confirmed to PEOPLE that there have been prior drownings on the lake. A Change.org petition has been created following Rivera's disappearance, urging officials to post warning signs for those interested in swimming.

The lake will remain closed to the public as long as the search for Rivera continues, Buschow said.

Naya Rivera's Ex Ryan Dorsey 'Can't Imagine Raising Josey Without' Her: Source .
"It's just a nightmare. Although he wasn't with Naya, it's Josey's mom. Josey needs his mom," a source tells PEOPLE about Naya Rivera's ex-husband, Ryan Dorsey“Ryan has barely slept,” a source says in the latest issue of PEOPLE. “It’s just a nightmare. Although he wasn’t with Naya, it’s Josey’s mom. Josey needs his mom.

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