Double killer Colin Howell has been questioned by police about a new claim of sexual assault.
The former dentist from Northern Ireland is serving at least 21 years in prison for murdering his wife and his former lover Hazel Stewart's husband.
Constable Trevor Buchanan, 32, and Lesley Howell, 31, were found in a smoke-filled garage in Castlerock in Co Derry in May 1991 in what was then thought to be a suicide pact.
Howell pleaded guilty to the murders in 2010 and implicated Stewart, who was convicted the following year.
A Police Service of Northern Ireland statement said: "A 59-year-old male was interviewed by police today and a file will now be prepared for the Public Prosecution Service (PPS)."