Detectives are investigating the circumstances surrounding the death of the father-in-law of double-murder accused dentist Colin Howell.
Henry Clarke, a retired company director, died just days before his daughter Lesley Howell and RUC officer Trevor Buchanan were murdered and their bodies discovered in a garage at the rear of his County Antrim house in an apparent suicide pact.
Police have charged Mrs Howell and Mr Buchanan’s spouses — renowned cosmetic dentist Colin Howell and his former lover Hazel Stewart — with their murders.
However it has also now emerged they are probing the circumstances surrounding the death of Mr Clarke.
A source close to the inquiry told the Belfast Telegraph that although Mr Clarke is believed to have died from a heart attack police feel that “under the circumstances it is now necessary to look deeper into the cause of his death”. He said the circumstances surrounding Mr Clarke’s death will be “thoroughly investigated”.
It is understood Colin Howell is to be asked to help police with the probe.
Howell has also been charged with drugging and indecently assaulting women and, as part of the deepening investigation into the dentist, detectives are planning to write to more than 200 of his former patients asking if they can assist with the investigation. They have checked Howell’s appointment lists and are expected to write to the patients over the next few weeks.
The PSNI refused to comment on the latest developments, however a spokesman said: “The named individual is under investigation. He has been charged with a number of serious offences. It would be inappropriate for police to comment further at this time due to the ongoing investigation and future court proceedings.”
The bodies of Mrs Howell and Mr Buchanan were discovered in a car filled with exhaust fumes in a garage at the rear of a holiday home in Castlerock belonging to Mrs Howell's late father in 1991. The house is in a row of cottages known as the Twelve Apostles.
Mrs Howell was lying heavily made up in the back seat of the car wearing headphones from a personal music stereo and listening to a gospel tape.
A pipe from a vacuum cleaner was attached to the exhaust, passed under a tailgate and in through an open window beside Mrs Howell's head. Constable Buchanan was in the front seat, and both clutched photographs of their children.
An inquest into the deaths at the time gave a verdict of suicide.
Almost 18 years later police have launched a murder inquiry after receiving new information about the deaths.
After being charged with the murders earlier this month Howell was remanded in custody while Stewart was released on bail totalling £15,000 after concern was raised that she might attempt suicide if remanded in the women’s prison at Hydebank.