The brother of a man murdered with a machete said "massive failings" meant a violent criminal was free to carry out the fatal attack.
Nicholas Churton, 67, was killed at his home in March 2017 by Jordan Davidson.
On Wednesday, the police watchdog said officers may have made errors when dealing with the case.
One officer recorded a robbery, which involves the use of threat or force, by Davidson as a theft, which may have put Mr Churton in danger.
James Churton said: "They let him out on bail. He was free to go and commit more crimes and murder my brother and I find that quite extraordinary."
Davidson, who is now serving a life sentence with a minimum of 30 years, had a long list of previous convictions and was out on licence when he killed Mr Churton.
North Wales Police had been in contact with Mr Churton several times in the 11 days before he was killed, including responding to his call that a man called Jordan had been in his home.
Mr Churton called police two days later to tell them the man's full name was Jordan Davidson. Four days later, he was found dead.
An Independent Office for Police Conduct report said an officer and a sergeant had cases to answer for misconduct about the way the complaint by Mr Churton was handled, advising him to speak to his friends and find out who the intruder was himself.
North Wales Police said it had reviewed risk assessment procedures as a result.
Mr Churton, who lives in Malpas, Cheshire, said: "I do feel very bitter about the whole thing. They had plenty of time to act on this. The guy should've gone back to prison, but he didn't."
Det Supt Dan Tipton said: "We will now be holding a number of formal disciplinary proceedings in line with the IOPC recommendations."