An 18-year-old male has been arrested over the death of a 62-year-old man who collapsed when he confronted a gang he caught breaking into a neighbour's car.
Mr Barrett was babysitting when he heard a car window breaking
James Barrett was babysitting his grandchildren when he heard the window of a car smash outside his home in Bingley Road, Anfield, Liverpool.
He collapsed as he chased the gang into Priory Road and died from a suspected heart attack on Friday night.
Merseyside Police said the youth was arrested on suspicion of manslaughter.
He was also being held on suspicion of causing criminal damage.
Police are appealing for help in tracing six youths involved who wore tracksuits, some with hooded tops.
Det Ch Supt Peter Currie, said Mr Barrett was just doing the "neighbourly thing" when he went to investigate the smashing glass at about 2250 BST on Friday.
Mr Barrett, who died about an hour later, leaves a wife, Mary, and two sons who live in the local area.
His family said: "We are completely shocked and devastated by this.
"Jim was a wonderful man who would do anything for anyone.
"As well as being a wonderful father, husband and granddad he was a true Liverpool supporter, with a real love of football.
"He will be greatly missed by all his family and many friends, who will remember him for his kindness, generosity and warmth."
Officers are appealing for anyone who might know the identity of the youths involved.