A man serving a life sentence without parole after being convicted of two murders is running for a US Senate seat.

Leonard Richards, 75, was convicted of killing his half-sister May Wilson in 1982, and of shooting dead his lawyer, Robert Stratton, in 1987.

He is serving a life term in Stillwater prison in Minnesota, where the law allows felons to run for federal office but bars them from vying for state-level office.

The sister of Mr Stratton told the Star Tribune newspaper that the Minnesota secretary of state's office could not keep Richards off the ballot.

She wants voters to be informed of Richards' history and intends to ask politicians to change the requirements, stating that "even one vote for this murderer is too many".


Bert Black, legal adviser for the Minnesota secretary of state's office, said the courts have ruled that the agency cannot stop a prisoner from filing an affidavit of candidacy.

"The only valid requirements are that you be of a certain age and that you live in the state on election day, essentially," Mr Black wrote in an email.

Richards is said to be aware of the loophole and has unsuccessfully tried to run for federal office in the past, the Star Tribune reported.

He previously ran in the Democratic primary for a congressional seat in 1992 - receiving more than 14,500 votes.

Richards subsequently ran again in 1994 and won more than 4,000 votes.