The two murder victims found within hours of each other at separate addresses in London last week have been named as Clinton Ashmore and Sharon Pickles.
Detectives have been searching for searching for Lee Peacock, 49, as part of their murder investigation and have asked people to contact police if they know of his whereabouts.
It follows emergency services being called to Ashbridge Street in Westminster, just after 9.30pm on Thursday after concerns were raised for the wellbeing of people inside the property.
Sharon Pickles, 45, was found with a knife wound to her neck and pronounced dead at the scene.
At 2.15am on Friday, police were alerted to reports of an injured man at a property in Jerome Crescent, about half a mile away.
Paramedics confirmed the 59-year-old, now identified as Mr Ashmore, had died after being stabbed in the neck.
Police suspect the deaths are linked.
Lead investigator Detective Chief Inspector Wayne Jolley said his thoughts are with the victims’ families, who have been informed of their deaths.
He said: “This is a shocking crime and we will not rest until we bring the person or persons responsible to justice.
“Key to that is finding Lee Peacock. We believe he knew both victims and urgently need to locate him to talk to him about their murders.”
He said detectives are “working around the clock” to find Mr Peacock but have not been successful so far.
People have been urged call 999 if they know his whereabouts.
“If seen, we would urge the public not to approach him, but to contact police as soon as possible,” he added.
Information can also be provided anonymously to Crimestoppers by calling 0800 555 111.