Democratic presidential contenders Beto O’Rourke and Cory Booker have slammed US President Donald Trump for promoting unfounded conspiracy theories about the apparent suicide of disgraced financier Jeffrey Epstein in his New York jail cell.

After the death on Saturday of Epstein, a millionaire charged with sex trafficking who once counted both Trump and former president Bill Clinton as friends, Trump retweeted a conspiracy theory video — a baseless claim from a conservative comedian that Clinton was involved in the death.

The hashtag #EpsteinMurder trended worldwide on Saturday. Joke images and memes — suggesting everything from a faked suicide to an orchestrated hit-job — were shared thousands of times throughout the day. Facebook, Twitter and YouTube were rife with unfounded theories about what may have happened to the financier.

Further rumours centred on how a man who had been found semi-conscious and with injuries to his neck just weeks earlier was able to take his own life. Initial reports said Epstein had been placed on suicide watch after that incident last month. This led many people to query how he could have died while being monitored so closely.

Prison officials later said that Epstein had actually been taken off suicide watch prior to his death. Conspiracy theories then started to converge on why this decision was made, rather than how he was able to take his own life.

Some of the most far-fetched conspiracy theories were accompanied by such hashtags as #ClintonBodyCount and #TrumpBodyCount, which both trended on Twitter over the weekend.

Referring to Trump’s own tweet, O’Rourke, a former congressman from Texas, said on CNN: “This is another example of our president using this position of public trust to attack his political enemies with unfounded conspiracy theories.”

O’Rourke said Trump was trying to shift the public’s focus away from the previous weekend’s two deadly mass shootings in El Paso, Texas, and Dayton, Ohio, which have led to new calls for gun restrictions and criticism of Trump’s divisive anti-immigrant and racially charged rhetoric.

“He’s changing the conversation, and if we allow him to do that then we will never be able to focus on the true problems, of which he is a part,” O’Rourke said from his hometown of El Paso.

Booker, a US senator from New Jersey, said Trump’s retweet was “just more recklessness”.

“He is giving life to not just conspiracy theories but really whipping people up into anger and worse against different people in this country,” he said on CNN.

The FBI and the Department of Justice’s Inspector General have opened investigations into the death of Epstein, who a source said had been taken off suicide watch. Last month, Epstein was found unconscious on the floor of his jail cell with marks on his neck, and officials were investigating that incident as a possible suicide or assault.

US attorney general William Barr said he was “appalled” to learn of the apparent suicide in federal custody. In a statement on Saturday, Barr said:

Mr Epstein’s death raises serious questions that must be answered.

Alexandria Ocasio-Cortez, a Democratic congresswoman from New York City and a leading progressive voice, tweeted: “We need answers. Lots of them.”

White House senior adviser Kellyanne Conway said investigation of Epstein should continue despite his death.

“Jeffrey Epstein has done some very bad things over a number of years, so let’s continue to investigate that,” she said on Fox News.

“I don’t think that somebody’s crimes and the accountability for that necessarily perish with them.”

More than a decade ago, Epstein pleaded guilty in Florida to state charges of solicitation of prostitution from a minor in a deal with prosecutors that has been widely criticized as too lenient.

Then in July, Epstein was indicted, federal prosecutors in New York accusing him of knowingly recruiting underage women to engage in sex acts with him, sometimes over a period of years while paying the women for each encounter. He pleaded not guilty.

O’Rourke and Booker are among two dozen candidates seeking the Democratic nomination to challenge Republican Trump for the White House in 2020. Nearly all of those Democrats have condemned Trump’s incendiary rhetoric for inflaming racial tensions and anger.

“We’ve seen people’s lives being threatened because this president whips up hatred. This is a very dangerous president that we have now,” said Booker.

Trump had retweeted on Saturday a message from conservative comedian and commentator Terrence K Williams, who said in part that Epstein “had information on Bill Clinton & now he’s dead”.

The baseless theory of the Clintons’ involvement has roots in a long-running conspiracy that originated in the 1990s, claiming that the couple secretly kill their enemies.

This was thoroughly debunked at the time by the fact-checking website Snopes: “We shouldn’t have to tell anyone not to believe this claptrap, but we will anyway.”

Clinton spokesman Angel Urena blasted Trump for making the suggestion.

“Ridiculous, and of course not true — and Donald Trump knows it. Has he triggered the 25th Amendment yet?” he said, referring to the procedures for replacing the president in event of removal or incapacitation.

Trump has a history of promoting conspiracy theories about political rivals. Even before he was a presidential candidate, Trump repeatedly questioned whether former president Barack Obama was born in the US, even after Obama produced a birth certificate proving that he was.

During the Republican presidential nomination race in 2016, Trump spread an unfounded conspiracy theory linking the father of rival US senator Ted Cruz to the assassination of former president John Kennedy — a claim Cruz denounced as a lie.