Our investigation into this story began when a recently-released prisoner Joe Mallia called us and said his cellmate, Dr Edward Erin, had asked him to kill his ex-mistress and their baby.
Erin was locked up for six years in 2009, when he was found to have drugged his former girlfriend to try and force a miscarriage. Erin had also asked Mallia, who he'd been locked up with in Belmarsh, to send a text message from her phone, taking back her evidence.
Because of his criminal past, Mallia didn't want to go straight to the police because he didn't think they'd believe him with no solid evidence. He showed me a couple of letters that Erin sent him in prison. It may not have been enough evidence for the police but I got a hunch that this story was worth pursuing.
He did not try to hide his criminal past from me and I believed he was telling the truth. He explained what Erin was trying to use him for and manipulate him into doing and I felt it was worth pursuing even though it was clear at an early stage this would be extremely complex thing to do.
He explained to me that Erin was a very clever man and that he would only talk openly face-to-face – not on the phone, not in a letter. He said he could get a visiting order to see Erin who was by this time in Parkhurst prison, and we arranged for the meeting to be recorded. Obviously filming in a prison is not something you'd take on lightly and we had extensive discussions at the newspaper.
We felt that this was a clear case of public interest because, if what Mallia was telling us was true, a very serious offence was going to be committed. The police and the courts have now backed us on that.
So I equipped him with a camera and drove him down to Parkhurst prison. He was able to record the conversation and returned the device to me. It was clear that Erin was planning to get revenge on his ex-mistress.
We made the decision to go to the police before publishing because we were concerned that his ex-mistress may be in danger when Erin realised Mallia was not prepared to carry out the task. Erin had made it clear that he had someone else ready to carry out the job, so clearly she needed to be warned and possibly be protected by the police.
I made it clear to him from the word go that, if we proceeded, I would expect him to fully cooperate with the police. We both gave evidence at Portsmouth Crown Court and Erin was found guilty. He gets sentenced next month.
I'm immensely proud of this, and other, investigations which are possible at the Sun. I've been here for 17 years and it was the only newspaper I ever wanted to work for because of its willingness to invest in investigative journalism like this.
This article first appeared in Press Gazette Journalism Weekly.