Naya Rivera: Police doing 'everything we can' in search for Glee star

Rivera's Glee co-star Heather Morris (right) appealed to police to let her search on foot

Police searching for Glee star Naya Rivera have told fans they are doing "everything we can" to find her, four days after the actress went missing.

Some fans vented their frustration on social media after police urged people not to turn up to join the search.

Co-star Heather Morris volunteered, but later said she would "hold off on the citizen search and rescue".

Divers and teams using sonar equipment are resuming the search on Lake Piru in California on Monday.

Rivera, 33, went missing on Thursday after going boating with her young son.

Police have said they believe she drowned in a "tragic accident", but many fans have not given up hope of her being found alive.

'Every available resource'

Sgt Kevin Donoghue, a spokesman for Ventura County Sheriff Department, told BBC News they were "putting every available asset and resource" into the search.

That includes using side-scanning sonar, divers, sniffer dogs, helicopters and remote-operated submarine vehicles equipped with cameras.

But they are working on the assumption that Rivera is dead, he said. That is based on what her four-year-old son told them on Thursday evening, after he was found alone and asleep in a boat.

"With the information he was able to provide, it was fairly conclusive that she was last seen in the water and she disappeared beneath the water," Sgt Donoghue said.

The boy's statement "was conclusive enough to be confident in our decision for the way that we're searching for her", he said.

He said the authorities would "never stop looking" for Rivera but added: "We're coming to that point in time where we may transition to a limited search, where we're only able to go out on the weekends or it might be certain days per month."

'Helpless and powerless'

Sgt Donoghue could not say when the search would be scaled back. That would be when "we've exhausted all of our resources searching the area", he said.

On Saturday, Morris, who played the wife of Rivera's character in Glee, called on the police to let her and friends search on foot.

"I understand your team is doing EVERYTHING in their power, but we are feeling helpless, powerless and want to help in any way," she wrote.

Morris posted another message on Sunday, saying she had spoken to Sheriff Eric Buschow and that she would "hold off on the citizen search and rescue until we get the go-ahead that they'll allow volunteers".

Pointing to the rugged terrain and hot weather, the Sheriff Department tweeted a message to anyone else who was tempted to try to help: "Our teams are well equipped and highly trained. We don't want to have to rescue you."

Sgt Donoghue said they had been concerned that Morris's original tweet "would garner a lot of support [from] people wanting to help".

He said: "While we completely understand that, it wouldn't help us with the search effort. We have a lot of sophisticated equipment on the lake so any more boats or people on the water would actually hamper our efforts, and the lake itself has a pretty rugged environment on the shore.

"There are steep slopes on the shore leading into the lake, so when you combine the rough terrain with the really hot weather, we just won't want to be in a situation where we're now having to rescue injured people who are trying to be helpful, but are in fact taking away resources from us."

Meanwhile Lea Michele, another former Glee star who last month apologised after being accused of making another actress's life "a living hell", has deleted her Twitter account, apparently after becoming a target for trolls.