Hampshire and Isle of Wight Chief Constable Alexis Boon told ITV in a statement: “Henry’s murder was a devastating tragedy, and our thoughts remain with his family and all those who loved him.
“I am incredibly sorry that in his final moments, when he needed us most, we failed him.
“For Henry’s family, this has been about more than the circumstances of one night.
“They have rightly raised serious concerns about the police response and their treatment throughout the investigation and since. No family should ever find themselves in this position.”
The Independent Office for Police Conduct (IOPC) confirmed its investigation into potential failures in the police response to Mr Nowak’s stabbing is expected to be concluded early next year.
However, a letter sent to the family by the watchdog in April said after “careful consideration of the available evidence” no officers “would be subject to conduct or criminal investigation”.
It read: “This was because there were no concerns identified in relation to officer actions and decisions that would be so serious as to justify the bringing of disciplinary proceedings, should they be proven or admitted.”
The letter added the decision not to investigate attending officers would be “kept under review throughout the life cycle of the case”.
The IOPC announced in July that two officers were under investigation for potential gross misconduct.
IOPC director of engagement Derrick Campbell said the watchdog was “committed to establishing the full circumstances of this case, including whether any of the officers involved should face disciplinary proceedings” and providing Mr Nowak’s family with answers.
“We are working hard to conclude our independent investigation as quickly as possible while ensuring we have robustly explored all lines of inquiry,” he said.
Campbell added investigators are in “regular contact” with Mr Nowak’s family members.
Digwa, 23, was jailed for life with a minimum term of 21 years.
Home Secretary Shabana Mahmood has announced an independent inquiry into the murder, led by former lord chancellor Alex Chalk, which will look at “any missed opportunities to intervene”.
Dear Henry: Our Fight For Justice, a Tonight special, airs on Thursday 5 November at 21:00 GMT on ITV, ITVX and the ITV News YouTube channel.