An investigation team led by a detective involved in the botched Katie Simpson murder probe was told not to release Natalie McNally’s killer from custody until his false alibi was checked out.
Former Detective Chief Inspector John Caldwell initially had a lead role in the investigation into the brutal murder of the pregnant Co Armagh woman in December 2022.
Natalie McNally was murdered at her home in Lurgan in December 2022 (Family Handout/PA)
Stephen McCullagh, Ms McNally’s former partner and father of her unborn baby, was found guilty of the grisly murder by a jury earlier this week.
The 32-year-old was found stabbed to death in her Lurgan home on December 19 2022 after McCullagh raised the alarm.
McCullagh, who was arrested and questioned by detectives, was later released from police custody after claiming he had been at home taking part in a YouTube livestream event.
It later emerged that while the livestream was broadcast on the internet at the time Natalie was murdered, it had in fact been pre-recorded by devious McCullagh.
Sources familiar with the case now say senior officers were urged not to release McCullagh from custody by a member of the investigation team until his ultimately false alibi was looked into.
Despite this, the killer was released.
“The basic thing to do is clarify alibis,” the source said.
“If McCullagh had given an alibi (of being with someone) that alibi would have been bottomed out at an early stage.
“He gave an alibi of an online video game, or being online, and it wasn’t clarified even though it was advised that they do clarify it before they release him.”
Days after his release from custody Ms McNally’s family were told McCullagh was no longer a suspect.
He later attended Natalie’s wake and it has been reported the twisted killer was allowed to spend time alone with his victim’s remains and that he later visited her grave.
The bare-faced killer also attended a vigil in memory of his former partner in her home town.
During McCullough’s trial it emerged that Natalie’s head was found near a dog bowl that “looked like it had been used to collect blood”.
It is understood a knife was found close to a Christmas tree, in a scene described as “gruesome”.
Mr Caldwell, who had led the investigation, previously featured in a BBC Spotlight programme broadcast in 2023, which focused on the suspicious death of Katie Simpson in Co Derry in August 2020.
Initially treated as suicide, her death was later upgraded to a murder investigation.
A man accused of raping and killing her, Jonathan Cresswell took his own life on the second day of his trial in April.
Chief constable Jon Boutcher later defended Mr Caldwell. In February 2023, Mr Caldwell was shot and seriously injured at a sports centre near Omagh, in Co Tyrone, by the New IRA.
He has since retired from the PSNI.
The Police Ombudsman said it has received no complaints in relation to the Natalie McNally murder.
A spokesman for the PSNI said: “As legal proceedings are ongoing, it would not be appropriate to comment.”