West Memphis Three. West Memphis Three freed from court. Three men convicted of the murders of three Cub Scouts are enjoying their freedom, nearly two decades after they were sent to prison in a controversial case which led to suspicions the children were killed in a Satanic ritual.

Doubts about the evidence against the trio, known as the West Memphis Three, had persisted for years, and led to the possibility of a retrial in 2012.

Instead, the Arkansas men were permitted to plead guilty to murder in exchange for time served, ending a long-running legal battle that had raised questions about DNA evidence and key witnesses - and attracted support from celebrities such as Pearl Jam singer Eddie Vedder.

The men - Jessie Misskelley, 36, Damien Echols, 36, and Jason Baldwin, 34 - entered the pleas under a legal provision that allowed them to maintain their innocence while acknowledging that prosecutors had enough evidence to convict them. "Although I am innocent, this plea is in my best interest," Misskelley said.

Prosecutor Scott Ellington said it would be "practically impossible" to put on a proper trial after 18 years. The mother of a witness who testified against Echols has publicly questioned her daughter's evidence. And a crime lab employee who collected fibre evidence at two of the defendants' homes has since died.

Since the original convictions, two of the victims' families have joined forces with the defence, declaring that the men are innocent, he added.

Echols said he and the others would keep working to fully clear their names. The men, who were teenagers when they were convicted, have spent half their lives in prison.

"It's not perfect by any means," Echols said of the arrangement. "But it at least brings closure to some areas and some aspects."

All three men were placed on 10 years' unsupervised probation. If they get in trouble again, they could be sent back to prison for 21 years, Mr Ellington said.

The three victims - Steve Branch, Christopher Byers and Michael Moore, all aged eight - were found naked and tied together in May 1993 in West Memphis, Arkansas. Rumours of Satanism swept the community in the weeks following their deaths. Branch and Moore drowned in about two feet of water, while Byers bled to death, and had been mutilated.