Detectives searching for missing Glasgow businesswoman Lynda Spence believe she has come to harm.

Ms Spence, 27, vanished nearly four months ago. She is said to have had debts running into six figures. It is thought she owed money to several people including dangerous criminals.

Ms Spence was last seen by her parents at their home in Partick, Glasgow, at around 6pm on April 13. She stayed at a friend's house that night, leaving at lunchtime the next day in her silver Vauxhall Astra – registration DV56 FKW – saying she was going to London.

She told her mum the same thing in a text message. Her parents eventually reported her missing. Detective Superintendent Alan Buchanan, of Strathclyde Police's major investigation team, said: "Since Lynda was reported missing, we have discovered a great deal about her business ventures, her finances and her lifestyle.

"However, despite numerous media appeals for information, no-one has come forward with any details that might assist us in tracing Lynda, and the likely scenario we are dealing with is that she has come to harm."

Ms Spence – known as Lynda Zefaj, Lynda Palmer and Lynda Reilly – did not contact her family on father's day or her dad's birthday.

Mr Buchanan added: "This is an agonising time for Lynda's family and we believe that if she was safe and well she would have made contact with them to end their torment.

Police tracked down a sighting of Lynda's car on the A77 at Floak, Renfrewshire, on April 20, a week after her disappearance.

And an old mobile phone she had stopped using some time before she went missing also turned up. The Nokia handset was found in a wheelie bin in Kilbirnie, Ayrshire, on June 2 and handed in anonymously.

Despite previous appeals regarding the phone and a police operation in the area, no-one has come forward with further information.

Mr Buchanan said he was disappointed by the poor public response.

He added: "Someone out there knows something and, for whatever reason, they haven't yet come forward.

"This could be for a number of reasons. It may be that the person assumes that we already know some crucial piece of information.

"We are trying to get the message across that people shouldn't assume what we might know, but should come forward no matter what information they have about Lynda."

Anyone with information is asked to phone the incident room at Anderston Police Office on 0141 532 3270 or Crimestoppers on 0800 555 111, where anonymity can be maintained.

People can also email lyndaspenceenquiry@strathclyde.pnn.police.uk or text 07864 178454.