A dog previously seized by police over fears it was dangerous has attacked and killed a man days after being returned to its owner.
It is thought David Ellam, 52, was trying to protect his own Yorkshire Terrier when the larger dog turned on him.
Police had seized the dog in June on suspicion it was a banned pit bull breed, but returned it on Wednesday.
A man, 29, thought to be the dog's owner has been arrested and bailed.
Mr Ellam suffered bites to his body on Riddings Road in the Sheepridge area of Huddersfield on Monday morning and was later pronounced dead in hospital.
Det Ch Insp Mark Swift, from West Yorkshire Police, said: "We believe that the victim was out with his own dog at the time of the attack near to his home address.
"His dog, a Yorkshire Terrier, was also injured during the incident and received emergency veterinary care."
The dog has since been returned from the vets.
Police said the larger dog was caught in a nearby garden and taken to kennels.
The Independent Police Complaints Commission said the matter had been referred to them by the force.
Carol Hanson, a friend of Mr Ellam, said: "We're lost for words, just devastated.
"It had only been out for five days, why did they let that dog back out, why did they let it go when it was vicious?"
Last week, a BBC investigation on the 25th anniversary of the Dangerous Dogs Act found 7,000 dogs had been put in kennels by police over the past five years.
West Yorkshire Police spent more than £550,000 on kennelling dogs over the same time period, with only the Greater Manchester and Merseyside forces spending more.
Speaking to the BBC following the man's death Caroline Kisko, from the Kennel Club, said she believed the act was "completely flawed".
She said the legislation had led to people "being fooled into thinking that just the way a dog looks defines its behaviour".
"The problem is that we've been given the idea that we are all secure because the Dangerous Dogs Act has vilified a certain type of dog and therefore, as long as they're illegal, we're all safe," she said.
"Any dog can be dangerous if it is wrongly handled and wrongly trained."