Naya Rivera: Police Say They 'Don't Know' If They'll Find Her Body

As the search and recovery operation continues for missing Glee star Naya Rivera, authorities are now saying that they "don't know" if they will find her body. Rivera, 33, went missing on Southern California's Lake Piru Wednesday after renting a pontoon boat with her 4-year-old son, Josey, who said that his mother never returned to the boat after they went for a swim.

According to Ventura County Sheriff's Office Sgt. Kevin Donoghue, who addressed the ongoing search for Rivera during a Thursday press conference, conditions in the lake may make it impossible for the actress's body to be recovered, PEOPLE reports. Reports have said that Lake Piru's bottom is filled with debris, including trees, and Donoghue said that "if the body is entangled in something underneath the water it may never come up." Conditions in the lake also make it difficult for divers to search, with Donoghue explaining that visibility "is terrible" and the trees, plants, and other debris at the bottom of the lake "makes it unsafe for divers and a complicated search."

As efforts to find Rivera halted overnight Wednesday and resumed Thursday morning, the Ventura County Sheriff's Department confirmed that the operation had transitioned from a search and rescue to a search and recovery. Rivera, according to previous statements from officials, is "presumed dead" and is believed to be a possible drowning victim. Lake Piru, where she went missing, has a history of accidental drowning deaths, recording seven such tragedies in just six years, according to a previous report from the Los Angeles Times. Many of those deaths are said to be due to inexperienced swimmers not wearing life vests or swimming in prohibited areas. According to the family of one drowning victim, the lake also poses dangers, such as "drop-offs and underwater cliffs that were not visible."

Speaking to PEOPLE, Donoghue that a thorough search of the surrounding shoreline and land made authorities "confident" that Rivera is still in the water. Donoghue told the outlet that emergency responders have searched the "shoreline for any clues whatsoever, any personal items, any footprints, anything that would indicate that she made it out of the water and because of the absence of those clues, that is why the focus of the search right now is in the water." He added that Rivera "could have suffered a medical episode," though they will not know the full story "until we find her."