A woman was found with severe head injuries in her home after a neighbour followed a trail of blood to her front door.
Police forced their way in to the house and found the woman lying in a pool of blood on her bed.
The woman, aged in her 50s, is thought to have been attacked in the street before struggling home and collapsing.
Splatters of blood were spotted by a neighbour on the pavement in Port Hall Road, Brighton, on Saturday.
He followed the trail to up the door of the three storey Victorian building before calling the emergency services.
Officers spent all day Saturday hunting for clues about how the woman received her injuries.
It is believed she was attacked on Friday night.
Officers carried out door-to-door inquiries and forensic experts were examining the scene yesterday.
One neighbour said yesterday: "We normally don't get this sort of thing around here, it is a very quiet area.
"Police have questioned just about everyone in the surrounding area and were particularly keen to find out about a gang of kids who had been roaming the streets."
Another said: "None of us know what happened at all. There was no particular noises that night although we quite often have kids going past.
"I think even the police have admitted it is a bit of a mystery and all the people I have spoken to who live here say the same.
"We didn't know the woman particularly well but it's never nice to hear that sort of thing has happened on your doorstep."
Police said they were keeping an open mind about the attack. A spokesman said: "Officers are conducting on-going investigations."
The woman is conscious but officers are still waiting to interview her.
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