WHISPERED phone calls overheard by a colleague of Anne Darwin in a doctor's surgery led police to re-open their investigation into the disappearance of her husband.
The Mail can reveal a tip-off was given to officers that Mrs Darwin, who had declared herself a widow six months after her husband John vanished, was making and receiving "a number of suspicious calls" at her workplace.
More John Darwin stories
It is understood the colleague contacted Cleveland Police, believing the person she was speaking to was John.
Detectives launched a fresh investigation in September into Darwin's disappearance.
It is believed the information was passed to police by a member of staff at the Gilesgate Medical Centre, in Gilesgate, County Durham, where Mrs Darwin worked.
Practice manager Dave Harris confirmed Mrs Darwin had been an employee there. He said: "She is a former member of staff but I don't really want to comment on it, as it is a police matter."
She also worked at a medical practice in Bear Park, County Durham.
Det Supt Tony Hutchinson said: "There was some information which was reported to us three months ago to suggest that perhaps there was something suspicious with regards to his disappearance."
A source close to Cleveland Police said: "The amount of calls Mrs Darwin was getting on her phone didn't raise any suspicions at first, but while the conversations she was having were always private, some of them were overheard.
"The tone of the conversations led the person that contacted the police to believe she was talking to the man who was supposedly dead, and the investigations basically started again from that point."