A 39-year-old man has been arrested on suspicion of murder after another man was stabbed in Leicester.
Ashley Johnson, 24, died on his way to hospital after he was found with a knife wound in Dannett Street at about 03:40 GMT on Saturday.
Leicestershire Police believe he was killed in a dispute between groups of young men.
CCTV footage of a Royal Mail van and a dark saloon has been published in a bid to trace possible witnesses.
Leicestershire Police said the vehicles were driving in the area around Fosse Road North.
Det Ch Insp David Swift-Rollinson said "a number of motorists" were on the roads at the time and asked for any witnesses to come forward.