A racing driver was chased down a suburban street and hacked to death with an axe.
Ryan Lowry, 36, suffered fatal injuries after being attacked by a man who had earlier been seen smashing up parked cars.
Shocked friends said the victim, a car salesman who founded a Porsche racing competition aimed at raising awareness of mental illness, had reportedly been "trying to help" his assailant before being attacked shortly before midnight on Thursday. A 31-year-old man known to Mr Lowry was arrested on suspicion of murder and later detained under the Mental Health Act.
Neighbours reported how they heard cars being smashed up in Partington, near Manchester, before seeing two men fighting.
The attacker is believed to have called the police before fleeing the scene, where the victim was pronounced dead.
Mr Lowry sold cars in Marple, near Stockport, and set up the CALM All Porsche Trophy racing series in support of suicide prevention charity the Campaign Against Living Miserably.
A spokesman for the series said: "Ryan and his dad Andy were well-known around the race tracks of the UK and made many friends during Ryan’s time as a racer and as race organiser."
Mr Lowry started racing cars in 2012 and competed at some of the most famous circuits in Britain including Silverstone, Brands Hatch and Donington Park.
On Facebook a former teammate wrote: "Will miss you buddy. I will be driving for you." Another friend, Damian Cottrell, said: "Just don’t know what to say, a great lad, fun to be around, always happy."
Mr Lowry’s family, who asked for donations to CALM in his memory, said: "It’s hard to believe how something like this can happen to someone like Ryan, who did not have a bad bone in his body.
"All he ever did was be there, in whatever way he could, for those that needed help.
"As a person full of kindness, strong principles and humour, he will be missed by so many."
The killing came ahead of another weekend of violence in Britain. A father to a newborn baby in Barnet, north-west London, was stabbed to death on his way to work on Saturday. The 24-year-old was found in a silver VW Polo just after 9pm.
Police believe the victim, from Edgware, was attacked in a nearby car park minutes before. No arrests have yet been made.
In Liverpool, a 20-year-old man was arrested after a 19-year-old was stabbed. Police had been called to reports of a fight between a number of men at around 4am on Sunday morning.
Figures released in January show there was a 7 per cent rise in offences involving knives or sharp instruments in the year to September. The 44 700 crimes police recorded in England and Wales was a record, the Office for National Statistics said.