The parents of a 22-year-old Dutchman found dead last week believe their son was drugged and robbed by a gang of criminals who had “no intention of killing him”.

Speaking at a memorial ceremony at Cresta Quay, St George’s Bay, where Justin Plette’s lifeless body was found on May 8, his father, Erik, claimed his son was the victim of a theft gone wrong.

“My son was not drunk that night. He was with friends and the next minute he disappeared. He was found without his mobile phone in a place that he would not normally frequent. There are many questions,” he said.

The family is basing the robbery theory on an account given by an unidentified youth who they believe survived a similar drug-induced mugging.

“The exact same thing happened to another person the following day. He woke up the following morning and started piecing it all together. Unfortunately for Justin, he never woke up,” his mother, Margit, told Times of Malta.

She said her son, who worked with the Bettson Group and had been living in Malta for the past eight months, was found lying on the rocks in a foetal position and his wallet and phone were missing.

Surrounded by friends and relatives, the Plette family said they had been in touch with the owners of a nearby diving school who had spoken to the unknown youth.

Mr Plette said the young man had woken up feeling groggy and with his phone and wallet missing. He had asked the diving establishment for assistance. When contacted by this newspaper, a spokesman for the diving school declined to comment.

Justin’s parents Margit and Erik Plette speaking last night.

The unknown young man did not report the issue to the police, nor did he leave any contact details.

The police said they were investigating and a magisterial inquiry was also opened.

“It is to be pointed out that no signs of violence were found on the deceased Dutchman. Nevertheless, the police are still waiting for the toxicological results of samples lifted during the post mortem,” a police spokesman said.

Both the police and the court-appointed experts were “exploring all avenues”, the spokesman added, noting that any information that could assist in the investigation would be welcome, even in confidence.

Sources close to the investigation said the scene of the incident could tally with a mugging.

The police were studying CCTV footage taken at the Paceville nightclub where Mr Plette was last seen. The CCTV camera at the beach club where his body was found had been out of order for some time.

During the memorial ceremony last night, the Plette family laid flowers on the ground where the body was found and hung photos of him on the wall. Friends spelt out his name in candles.

Mr Plette’s body will be flown to the Netherlands this weekend and he will be buried next week.

His mother said she had spoken to him a few hours before he died. He had told her about a fruitful conversation he had just had with his boss about his future in Malta.