The prison officer, Kay Holmes, disappeared after handing in her resignation and her uniform at at Stanford Hill open prison at Eastchurch, on the Isle of Sheppey in Kent.
The escapee, Danny Wayne Gilpin, was given a life sentence at the Old Bailey in July 1993 for murdering a rent collector. He escaped on 3 July - just six weeks before he was due before a parole board.
Mrs Holmes's husband Edwin, a lorry driver, tried to hang himself at the couple's home in Sittingbourne, Kent, but police broke into the house and resuscitated him after being alerted by his daughter, a police spokesman said.
Yesterday Mr Holmes's condition was described as "stable" in a hospital at Gillingham, Kent.
The police spokesman said: "It is believed Gilpin is in the company of a woman who worked at the jail as a prison officer.
"The woman resigned from her job and then went missing from the family home in Sittingbourne."
A source at the jail said: "It certainly sounds like a bizarre thing to happen, but staff and inmates are often thrown together for long periods of time.
"Sometimes the professional line which neither can cross can be eroded, until it virtually disappears, and that's when things start to get dangerous and personal.
"The police have been informed of this, and are now conducting their own investigations."Reuse content