CHICAGO - A US couple wrongly jailed for 21 years on charges of sexually assaulting children as part of a satanic cult, received $3.4 million Wednesday from the state of Texas, months after prosecutors acknowledged their innocence.

Operators of a daycare facility, Dan and Fran Keller were at the center of a sensational case in 1991, accused by children of abuse and dark rituals that included dismembering babies and torturing pets.

Authorities later acknowledged that the children were improperly interviewed, triggering false memories, amid a climate of fear fueled by a belief around the nation that satanists were preying upon children.

The physician who claimed to have discovered physical evidence of abuse also acknowledged in 2013 that he had made a mistake in assessing the source of one of the children's injuries.

The Kellers were freed from prison that year, but not fully cleared of the charges against them until last June, when prosecutors finally declared them innocent.

By Texas law, both are entitled to $80,000 compensation for each year they spent in prison. They picked up a $3.4 million payment on Wednesday, their lawyer Keith Hampton told AFP.

"They are happy," Hampton said.

The couple had been living in poverty since their release, unable to find work in their advanced age and with their past legal troubles, according to the Austin American-Statesman newspaper.

"This means we don't have to worry about pinching pennies on Social Security, and late bills. It means we will actually be free. We can start living - and no more nightmares," Fran Keller, 67, told the newspaper.

She broke down in tears Tuesday in front of news cameras as she found out on the phone that the state would provide compensation.

"I really would like an apology from the state. But since we're not going to get it verbally, this will be good enough," the American-Statesman reported Fran Keller as saying.

Between 1991 and mid-2016, Texas had paid 101 wrongfully convicted prisoners $93.6 million, according to the Texas Tribune.