POLICE unknowingly sat on crucial evidence in the Alena Grlakova murder investigation for months as the double killer remained free — and downloading child abuse images.
Gary Allen was immediately linked to Alena in January 2019, charged with other offences and had his home raided.
But the factory worker — who was sentenced yesterday for killing Swinton mum Alena and murdering 29-year-old Samantha Class in 1997 — was released over two alleged breaches of a sexual offences prevention order (SOPO) when the Crown Prosecution Service dropped the case against him due to “insufficient evidence”.
As police continued to hunt for missing Alena — once searching close to the Parkgate spot where her body had been dumped — Allen remained at liberty.
He went on to access child abuse images and twice breach his SOPO again by visiting sex websites and having a device capable of clearing his internet history.
It was not until April 2019 that police listened to vital evidence seized from his home in January — “chilling” voice recordings of him threatening the mum-of four at his Parkgate flat on Boxing Day, 2018.
Lead investigator, Det Chief Insp Mark Oughton, said: “The recordings were brought to my attention in April.
“A police officer listened to them and realised the significance. They had been recovered from his flat in January.”
The detective (pictured) said the delay had not been an error and he had no regrets over his handling of the investigation.
“It was a very complex enquiry,” he said. “Hindsight is wonderful.
“Gary Allen was only one part of the investigation. We had officers trying to track Alena’s movements. Had she gone to Europe? Had she gone back to family?
“These things take time. It was not an error. I don’t regret it. There were many facets of the investigation. We didn’t know if she was dead until April 2019.”
The detective said the moment he listened to the “chilling” voice recordings — in which Allen threatened to “beat the f****** living s***” out of Alena — would be etched in his memory for the rest of his career.
He added: “When I listened to them, that was the key point when it became a murder enquiry. At that point [Allen] became a suspect.”
Police still do not understand why Allen recorded himself on an MP3 player threatening Slovakia-born Alena in the hours before her murder — but the recordings played a key role in proving his guilt.
Mr Oughton said: “On the last [recording], he basically said if Alena came back to his door he would cause her severe harm, and I firmly believe she went back to that address and he killed her that Boxing Day night.”
In the recordings, Allen can be heard screaming at vulnerable Alena to get out of his flat after she asked for a drink of water.
“He chose to record his interactions and, clearly, they were very useful to the police investigation and the tipping point that made me declare it a murder investigation,” he said.
The recordings also led police to review search sites and attention was focused around Allen’s Parkgate home for a second time.
Two officers discovered Alena’s body in the Old Sough stream — close to where land searches had been carried out two months earlier. Allen was first linked to Alena when she was reported missing in January.
He was arrested on January 26 after her phone records showed that she had been in contact with him.
“It was suspected, at that point, that Alena was a sex worker, and Gary Allen had conditions not to associate with sex workers through his SOPO,” said Mr Oughton.
Police also found clearing software on his mobile phone — a further breach of his SOPO.
But Allen was released on court bail on January 28 and the case was discontinued by the Crown Prosecution Service in February.
A CPS spokesperson said: “The CPS has a duty to keep its cases under constant review.
“In this case, there was insufficient evidence provided to the CPS at the time of the hearing in February 2019 for a realistic prospect of conviction, and so the case was discontinued.”
Mr Oughton said on the software clearing charge, the CPS had deemed there was insufficient evidence for a successful prosecution. And on the possible breach of conditions barring Allen from contact with sex workers, he said: “We could not prove [Alena] was a sex worker because we could not find her.”
He said a “robust risk management plan” had been placed around Allen, with police visiting him regularly at his home — but he went on to commit three further offences.
It was discovered upon his arrest for murder on April 10 that he had been browsing “sex sites” on his phone and had a device capable of clearing his internet history.
Allen was also found to be in possession of child abuse images.
At this point, he was remanded into custody for the three offences but it was not until October that he was charged with Alena’s murder. Humberside Police charged Allen with the murder of Samantha Class on June 11, 2020.