The family of one of the victims of Bryan Kohberger has hit out after it emerged that he was challenging his conviction for four murders of students in the US state of Idaho.

Kohberger was sentenced last year to four consecutive terms of life in prison after pleading guilty to charges of murder in the November 2022 killings.

In recent days, Kohberger told the New York Times he was taking back his plea, which was made to avoid the death penalty. He said it had rested on "false promises and blatant disinformation".

The family of Kaylee Goncalves, one of the students who was killed, said that Kohberger was a "narcissist", who appeared to have changed his position.

"He chose not to leave his fate - or the facts of the case - to a jury," the statement from the Goncalves family said.

"He never cried foul, never claimed he was uninformed or pressured, and never suggested there were problems with the discovery materials he and his counsel had reviewed for two years that should have been challenged."

The Goncalves family went on to say "the real tragedy" was the amount of attention that Kohberger was now receiving at the expense of the victims.

Kohberger was convicted of stabbing to death housemates Kaylee Goncalves, Ethan Chapin, Xana Kernodle and Madison Mogen, who all attended the University of Idaho, in their off-campus home on 13 November 2022.

The case shocked the small student town of Moscow and made national headlines for almost two months before Kohberger was arrested.

Kohberger was a criminology doctorate student at a different institution, Washington State University.

He never shared a motive with the court and it is not clear why he drove to another campus to brutally stab four students.

Investigators were unable to link him to the victims, although they presented compelling evidence that put him at the scene of the crime.

In his statement to the New York Times, declaring his new intention to enter a not-guilty plea, Kohberger protested his innocence and said he was offering prosecutors another chance to file for the death penalty if they wanted to.

Idaho Attorney General Raúl Labrador paid tribute to the victims' families, saying they had "already endured unimaginable loss and now must face today's deeply painful news".

Labrador's statement added: "My office stands ready to do whatever is necessary to ensure justice is fully carried out."

But Kohberger's attempt to reverse his plea is a longshot, experts say.

"He told the judge under oath at the plea hearing that he understood the deal, was acting voluntarily, and was pleading guilty because he was guilty," Sam Newton, associate professor at University of Idaho College of Law, told the BBC.

"That's a real problem, since courts don't take kindly to walking a voluntary plea back without hard proof that something went seriously wrong behind the scenes."