A man who was shot dead in Libya grew up in Comet country.

The body of Mark De Salis, who lived in Shackleton Spring in Stevenage and was a pupil at The Thomas Alleyne School in the town, was discovered with the body of 47-year-old New Zealander Lynn Howie on a beach near the coastal area of Mellitah on Thursday.

Mr De Salis, 46, had worked in the capital Tripoli for six years, bringing generators to the area to provide electricity.

It is understood the pair, who are described by his family as “close friends”, were enjoying a picnic when they were both shot in the back of the head. The reason for the killings is not yet known.

In a statement issued by the family of Mr De Salis, they say they are “shocked and devastated” by his death. The statement reads: “Mark enjoyed his work in Tripoli and liked the Libyan people.

“Mark enjoyed travelling and had travelled extensively. He was a decent and incredibly loyal man and he was loved by many. He will be sadly missed by his family and friends.

“Mark was with a close friend from New Zealand who was also killed and our thoughts are with her family at this sad time.”

Richard Stephens, secretary of the Old Alleynians Association - The Thomas Alleyne School’s alumni group for former pupils - said Mr De Salis was a pupil at the school in the early 1980s. “It’s horrible news,” he said. “It’s a shock, and for someone who was still relatively young it’s even worse.

“He was the youngest of five boys, and I was at school with his older brother, Clive. Dorothy, their mother, taught geography at the school for 28 years.

“Mark served in the RAF, including time in Bosnia. He had a very adventurous spirit. He was always very modest about his time in the RAF but I know he formed part of the British and UN peacekeeping operations in Bosnia. He was placed in danger several times. When he left the RAF in the 90s I know he wanted to go out and see the world.”

Childhood friend John Woolford said: “We grew up next door to each other. He was lovely. He was shy; a nice guy. He was such an explorer.”

The UK Foreign and Commonwealth Office (FCO) is calling on the Libyan government to conduct a full investigation into the murders.

“We are deeply saddened by the murders,” said an FCO spokesman. “Our Chargé d’Affaires has raised the shooting with the Libyan authorities and we are liaising closely with them on follow-up.

“We call upon the Libyan government to carry out a thorough investigation into this tragic incident and to continue to do all it can to bring to justice the perpetrators of this appalling crime, as it strives to build strong rule of law in Libya.”