A man has been arrested on suspicion of murdering two women, five years apart, including his girlfriend who died after he rolled over as they slept.
Robert Trigg, then 47, was ruled at an inquest to have accidentally crushed 52-year-old Susan Nicholson after they cuddled up on a sofa in April 2011.
But after new forensic evidence emerged, a re-investigation into how she died was begun earlier this year, and Sussex Police have now linked Ms Nicholson's death with that of 35-year-old Caroline Devlin five years earlier.
A post-mortem examination following Ms Devlin's death in March 2006 found she died from natural causes and, as a result, an inquest was not held into her death.
Ms Nicholson died at her flat in Rowlands Road, Worthing, West Sussex, and Ms Devlin in Cranworth Road, Worthing - the same seaside town where Trigg, now 52, lives.
Ms Devlin, a mother of four, was found dead in bed after being brought a surprise breakfast on Mother's Day, according to a local news report at the time of her death.
At the 2011 inquest into Ms Nicholson's death, West Sussex coroner Michael Kendall said there was no evidence she had been the victim of violence and recorded her death as an accident.
Trigg, whose name was confirmed by sources, has been freed on police bail until February 20 pending further inquiries by the Surrey and Sussex major crime team.
A Sussex Police statement said: "The arrest follows a re-investigation which began earlier this year of the death of Susan Nicholson which, following a police investigation in 2011, an inquest had found to have been accidental.
"They have also investigated the death of Caroline Devlin, which was found at the time in 2006 to have resulted from natural causes following a post-mortem. There was therefore no inquest into this death.
"This current investigation followed new forensic information we received about the 2011 death, which may have some features in common with the 2006 death.
"Families of both deceased have been kept informed about the investigations and are also being kept informed about this latest development."