Investigators returned to Dingli Cliffs yesterday in a bid to recover the blue backpack German teenager Mike Mansholt was carrying when he was last seen at the Sliema hotel he was staying in.

A drone was used in the search but the backpack was not found.

Sources close to the investigations said that although foul play has been ruled out, the police were looking desperately for the teenager’s mobile phone, which could shed more light on his final moments.

Mike Mansholt, whose body was recovered at Dingli yesterday.

In a Facebook post the German's girlfriend thanked the police and volunteers involved in the search and appealed for information about the haversack .

"This is important to us because: Mike and I (Antonia) took many pictures and videos together that are documenting his last week and also our last week we could have together. It was a wonderful time. We, his family, see a way to experience his last days with him together, if we could just have these pictures and videos. We only care about his mobile phone and GoPro, not even about the camera, just the memory cards inside," she said.

"Please, if you happened to have found this haversack, just contact us. If you have the feeling that the manner or style wasn’t absolutely legal, we do not mind about that at all! We won’t announce that to the police, we will not bring you in any trouble. We simply would be very, very thankful. Please, help us keeping our memories. It would mean the world to us."

The 18-year-old adventurer, who came to Malta on holiday on July 8, was found dead at the foot of Dingli Cliffs on Tuesday, just minutes after his older brother, Daniel, had called a press conference and appealed for help in the search for him.

Mike had been reported missing last Friday after missing his flight home.

The sources said Mr Mansholt was found without his running shoes a few metres from his rented bicycle. The police believe he either lost his shoes when he fell or else removed them afterwards.

Foul play has been ruled out, but the police are looking desperately for the teenager’s mobile phone

It was also established that the damage that was apparent on the bicycle was not compatible with a fall from a height.

Mr Mansholt’s relatives accompanied the police to Dingli Cliffs yesterday to assist in the search for his personal belongings.