According to his lawyers, the serial killer known in Britain as the Yorkshire Ripper is seeking his freedom from prison.

The Times of London reported that lawyers representing Peter Sutcliffe told the High Court in London expert evidence on his psychiatric state could help lead to his release.

The lawyers, citing a report written by a psychiatrist treating Sutcliffe in 2006, argued their client was too mentally ill to have been responsible for the slayings of 13 women. The psychiatrist's report concluded Sutcliffe would be unlikely to offend again if he received proper treatment.

Sutcliffe was convicted in 1981 of 13 counts of murder and seven counts of attempted murder in Yorkshire and Greater Manchester in the late 1970s and early 1980s. He was sentenced to 20 life sentences and told he would serve a minimum of 30 years.

Since 1984, after being transferred from prison suffering with paranoid schizophrenia, he has been held in a high-security psychiatric hospital. He refused treatment until 1993 when the government ruled it must be given forcibly.

According to 63 years old Sutcliffe, he believed God gave him a mission to kill prostitutes, though not all of his victims were prostitutes. (With Inputs from Agencies)