Police launched a murder inquiry last night after a man was found dying in the street from a single stab wound to the stomach.
Today a 29-year-old man was arrested at an address in Worthing and taken to a custody centre where detectives were waiting to interview him.
The victim, Chris Stones, is believed to be a 27-year-old father, originally from Manchester.
He died in Pavilion Road, Worthing, shortly after 11pm.
Detective Chief Inspector Graham Pratt, leading the investigation, codenamed Operation Large, said it appeared to be a vicious and unprovoked attack.
Neighbours said they heard moaning and groaning coming from the victim and at first thought he was a drunk who had collapsed.
But medics were shocked to discover Mr Stones, who was lying on the pavement, had been knifed and murder squad detectives were called in.
Police want to question a 6ft man, believed to be local, who was wearing a dark jacket.
Mr Pratt said: "We appeal to local people who may have seen this to provide us with information."
Police spokeswoman Jill Pedersen said: "Police were called by the ambulance service at 11.18pm.
The victim had been walking home with a male friend, having been out socialising.
"His friend went into the house and came out again to find him in the street.
"Anyone who may have seen an altercation in the road between 11pm and 11.15pm is asked to contact the incident room."
The scene in Pavilion Road was sealed off all night as forensic experts searched the area, opposite the entrance to Worthing Pavilion Bowling Club.
One resident said police in riot gear approached a terraced house near the scene, while another said he saw three adults and a child being taken away.
Gordon Knowles, 37, of Pavilion Road, said: "I heard a lot of moaning and groaning at about 11.30pm last night. I went out with the dog and saw a man lying on the floor with somebody giving him heart massage.
"About 20 minutes later, I saw three adults and a little child getting into two police cars."
He said the street was quite busy at the time with people walking home from nearby pubs.
Steve Badzek, 30, also of Pavilion Road, said: "I heard a chap on the pavement moaning and groaning. His friend was trying to get him up.
"I thought he was on the floor drunk and heard an ambulance being called."
Katherine Morris, a 24-yearold Northbrook College student, of Pavilion Road, said: "I heard a dog barking and this guy grunting. Then I heard a guy on the phone walking past quite fast.
"As far as I am concerned this road is very dodgy. I hear a lot of strange goings-on."
Neighbour Clive Rice watched police in riot gear and a dog handler surround a neighbouring house.
He said: "Police with shields were hiding behind a hedge and went into the house. All I heard was banging on the door and an officer going up the alleyway with a dog.
"I couldn't believe it. I woke my wife."
As residents woke this morning many were stunned to find a 50-yard stretch of Pavilion Road cordoned off with police tape.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article