Jeffrey Epstein’s apparent suicide has prompted major investigations into the circumstances of his death at the Metropolitan Correctional Center in Manhattan, as outlandish theories, including one backed by Donald Trump, circulate.

Some politicians, such as Alexandria Ocasio-Cortez, called for answers without theorising and expressed concern for Epstein’s victims. “We need answers. Lots of them,” she tweeted.

Others regretted that Epstein would no longer be able to incriminate others. “How many other millionaires and billionaires were part of the illegal activities that he was engaged in?” asked the New York mayor, Bill De Blasio.

In the hours after the death of the financier, who was accused of sexually abusing young girls, wild theories began to emerge and the hashtag #EpsteinMurder was trending worldwide.

Trump, who has a history of retweeting conspiracy theories, retweeted a post sceptical that Epstein had killed himself and included the line “#JefferyEpstein had information on Bill Clinton & now he’s dead”.

‘We live with scars’: accusers demand Epstein’s death not derail investigations Read more

The retweet was criticised on Sunday by the Democratic presidential candidate Beto O’Rourke, who said it marked the president’s latest bid to change the national conversation.

“This is another example of our president using this position of public trust to attack his political enemies with unfounded conspiracy theories and also to try and force you and me and all of us to focus on his bizarre behaviour,” O’Rourke told CNN. “He’s changing the conversation if we allow him to do that then we will never be able to focus on the true problem, of which he is a part.”

When asked on Fox News Sunday about the president’s retweet, White House counselor Kellyanne Conway said: “I think the president just wants everything to be investigated.” She also said “It’s not for me to go further than where the DOJ [Department of Justice] and FBI are right now,” though that’s what Trump appeared to be doing in his retweet.

Trump is among the powerful people who knew Epstein, who also include the former US president Bill Clinton and Prince Andrew. Trump once described Epstein as a “terrific guy”. The post he retweeted was by the actor and comedian Terrence K Williams, who later insisted he was not a “conspiracy theorist and whacko”.

Fuelling conspiracy theories is the expectation that the inquiries into Epstein’s death – which the US attorney general, William Barr, has said he was appalled could have happened – will look at suggestions he had previously tried to kill himself.

It has been reported he was previously on suicide watch for around a week last month. The FBI and the Department of Justice’s office of the inspector general would investigate the circumstances surrounding Epstein’s death, Barr said.

The Republican senator Rick Scott of Florida, the state where some of Epstein’s alleged sexual abuse took place, suggested others might have been involved in Epstein’s death when he called on officials to explain what happened at the prison.

“The Federal Bureau of Prisons must provide answers on what systemic failures of the MCC Manhattan or criminal acts allowed this coward to deny justice to his victims,” he tweeted.

The former New York mayor Rudy Giuliani, now an attorney for Trump, raised several questions about Epstein’s death. “Who was watching? What does camera show? … Follow the motives,” he tweeted on Saturday afternoon.

Prison cameras are likely to have recorded the circumstances of Epstein’s death, according to Preet Bharara, the former federal prosecutor in Manhattan. “One hopes it is complete, conclusive, and secured,” he tweeted.

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Some theories around Epstein have been easily debunked.

Days after his arrest last month, online memes and Facebook statuses wrongly claimed that the Obama administration forged a once-secret deal in Florida in 2008 which allowed Epstein to plead guilty to soliciting a minor for prostitution to avoid more serious charges. The deal was executed before Obama took office, under the former president George W Bush.

Meanwhile, a manipulated photo shared by thousands on Twitter and Facebook falsely claimed to show Epstein with Trump and a young Ivanka, the president’s daughter.

Trump and Clinton have both denied knowing anything about Epstein’s abuse. Trump has acknowledged Epstein’s acquaintance but said he “had a falling out with him a long time ago”.

Clinton spokesman, Angel Ureña, said last month that the former president knew “nothing about the terrible crimes Jeffrey Epstein pleaded guilty to in Florida some years ago, or those with which he has been recently charged in New York”. He said Clinton had taken four trips on Epstein’s plane in 2002 and 2003, and that staff and his secret service detail travelled with him each time.

The MSNBC host Joe Scarborough was forced to clarify what he meant by one of his tweets after being accused of spreading a conspiracy theory. He had written: “A guy who had information that would have destroyed rich and powerful men’s lives ends up dead in his jail cell. How predictably … Russian.”

He later tweeted that “treating a glib comment on Twitter like it’s the front page of the New York Times shows just how little perspective people have in this swirling media ecosystem”.

Epstein, 66, had been denied bail and faced up to 45 years in prison on federal sex trafficking and conspiracy charges unsealed last month. He had pleaded not guilty and was awaiting trial next year.

Associated Press contributed to this report

• In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found atwww.befrienders.org.