A married couple found murdered in their semi-detached home had suffered “serious injuries”, police said.
A murder investigation was launched after the bodies of a 54-year-old man and a woman, 52, were discovered at the house on Tuesday.
Officers had been called to the address in Moat Road, Oldbury, West Midlands, at about 4am, following concerns for their welfare.
A 25-year-old man, who detectives said was known to the couple, was arrested in nearby Smethwick on suspicion of murder and remains in police custody.
West Midlands Police said a post-mortem examination would be carried out in due course to formally identify the couple and establish causes of death.
Police said the couple’s deaths were being treated as a “domestic incident” and there was no threat to the wider community.
However, officers are now appealing for the public’s help in tracing the couple’s distinctive yellow Toyota Aygo car, which is still missing.
The vehicle, with the registration number SD17 KKY, may have been abandoned or offered for sale, according to police who are hoping to jog people’s memories.
Detective Inspector Hannah Whitehouse, who is leading the investigation, said: “We are working hard to identify and support the relatives of the two people who have lost their lives.
“Our investigation has already made good progress, but I really need the public’s help in tracing the couple’s car.
“If anyone has seen it being driven, or been offered it for sale, or has seen it abandoned somewhere, we need to know as soon as possible.”
All day, forensics teams had been at the address, where a smashed window panel could be seen propped against the front porch doorway.
A blue forensics tent was put up on the paved driveway and a light had been switched on in an upstairs room.
At around lunchtime on Tuesday, a private ambulance was reversed up to the front door and the couple’s bodies taken away.
Meanwhile, neighbours described their disbelief at the news.
Resident Linda Hyde, 68, said: “It’s an awful thing for them and the family left behind.
“It just goes to show you don’t know what’s going on behind closed doors.”
Another neighbour, who lives opposite and declined to be named, said the man who lived there had remarried in the last few months.
He said: “He was a nice guy – it’s a real shock.
“I saw the police outside but I didn’t know what happened.”