A French former soldier questioned in connection with the murder of a British engineer in the French Alps has been found dead after apparently killing himself, according to reports.

The 50-year-old man, who has not been named, was questioned by police in April last year over the shooting of Saad al-Hilli, his wife Ikbal and her mother Suhaila al-Allaf, on a forest road in Chevaline in September 2012.

A local cyclist, Sylvain Mollier, was also murdered.

The man, who fought with the Foreign Legion and was a parachutist and trained marksman, left a note outlining how he felt about being questioned by detectives over the massacre, the Daily Mail said, and local reports suggested firearms were found at his house in the village of Ugine.

He left a "six- or seven-page note" saying he was "disturbed" by the questioning, which "made him feel like a suspect", Eric Maillaud, the prosecutor for the Annecy area in eastern France reportedly said.

The man was questioned for two hours in April 2013, according to Maillaud, because he was "linked to Mr Mollier's family".

Iraqi-born Mr Al-Hilli, 50, and his 47-year-old dentist wife were from Claygate, Surrey.

Their bodies, along with that of Mrs Al-Hilli's mother, were found shot dead in their BMW on a remote forest road by cyclist Brett Martin.

The Al-Hilli's eldest daughter, Zainab, was shot in the shoulder and beaten but survived. Her four-year-old sister, Zeena, lay hidden under her mother's body and was only discovered eight hours after the murders.

Mr Al-Hilli's brother, Zaid, was arrested on suspicion of murder in June last year but was told in January that he would face no further action after police found there was insufficient evidence to charge him with a crime.

Mr Al-Hilli, from Chessington, Surrey, publicly protested his innocence in October and accused French investigators of a cover-up, saying: "They are covering up for someone in France in that region and they know it."