After years of painstaking investigation into the grisly confessions of a graying man in a wheelchair inside a Los Angeles County prison cell, the FBI have announced that Samuel Little, who has admitted to strangling vulnerable women across the country for decades, is the most prolific known serial killer in American history.

Little, 79, has confessed to 93 murders, the FBI said. The agency said in a statement that it had verified 50 of the killings and that it believed "all of his confessions are credible".

America's worst serial killer Samuel Little's disturbing TV interview
Killer dad