The family of a father-of-two from north west London who vanished four years ago today (12 January) have offered a £5,000 reward for information on what happened to him.
Robert Duff, 41, from Kilburn, disappeared in January 2013, failing to attend a family celebration for his daughter's 18th birthday.
He was last seen on CCTV withdrawing money from a cash machine outside a Sainsbury's in Holloway Road, north London, at 11.12am on 12 January 2013.
He has not been seen since, with his phone unused and his bank account untouched.
On the day of his disappearance, Duff accidentally left two voicemail messages on his daughter's phone in which two other voices could be heard.
One was a woman and the other a man with a Scottish accent called Gary or Gal. A dog could also be heard in the background.
Robert's family, including his two daughters, say they are distraught and extremely worried for his welfare.
In a statement, Robert's family said: "We miss Robert terribly and he is constantly in our thoughts. The hardest thing is not knowing where he is or what has happened to him.
"Hearing his voicemail message is all we have. Someone must know something about Robert's disappearance and our whole family is making this plea to urge anyone who does know anything to end this hell for us by sharing any information they know."
Duff's mother, Helen, 63, said they were offering £5,000 from their savings to find out what happened, the Evening Standard reported.
Detective Inspector Lee Dawson, of Brent Police, said: "I urge anyone with any information at all on the whereabouts of Robert to call us immediately. This is a very distressing time for Robert's family so please help them by coming forward with any information that will help us trace Robert, no matter how old this information is or how small it may seem.
"I also appeal to Robert – if you are in any trouble then we can help you, just call your family or the police and let us know you are safe."
Robert is described as a white man, around 5ft7ins to 5ft8ins tall, of slim build with short brown hair.
He is known to frequent the Holloway, Kentish Town, Islington and Camden areas, however at this stage Robert has been missing for four years and may have visited other areas, police said.
Anyone with any information about the circumstances of Robert's disappearance, the events leading up to his disappearance or any information since his disappearance, should call Brent's Missing Persons Unit on 020 8733 3734 or 020 8733 3092. Alternatively contact Missing People on 116 000.