The heartbroken parents of a six-year-old boy with learning difficulties have put up a GBP 26,000 bounty on a mugger who caused the boy’s drowning.

Police say they have not turned up a single clue in the early morning attack on the boy’s dad as he took him for a walk in the park in his buggy.

Now the lad’s parents have offered the huge, EUR 30,0000 (GBP 26,000) reward, to draw in information about the mugger.

Florian Apler, 37, was pushing his son Leon in his buggy when he was reportedly struck on the back of the head with a bottle by an unknown assailant in Sankt Johann in Tirol, in the state of Tyrol, in western Austria, at around 4am on 29th August.

While the father fell to the ground unconscious due to the hit, the boy – who reportedly suffered from the rare genetic condition SYNGAP1, characterised with severe learning disabilities – reportedly wandered around disoriented.

The father came to at around 5.20am after he was found by a passerby and immediately looked for his son, who at that point was nowhere to be found.

His mobile phone and empty wallet, however, were found in the immediate vicinity of the crime scene.

Leon’s lifeless body was discovered in the nearby Kitzbueheler Ache river at around 6.30am, after he reportedly climbed out of his pushchair and fell into the stream of water.

He was buried at the Waidring cemetery in Tyrol a week later, after the autopsy confirmed there were no traces of external violence on the boy.

But now the heartbroken father and his wife Sandra posted an appeal on social media offering a reward for “clues, abnormalities and private cameras” leading to the fugitive.

The post stated: “Information or clues that lead to the investigation of the offender according to police confirmation will be rewarded with the payment of a total of EUR 30,000” (GBP 26,000).

It added: “In order to support the police in solving this crime, we ask for your help.

“Pease report any kind of useful information and tips to the telephone number of the press service of the LKA [State Criminal Police Office] on 0043/59133703333 or any other police station.”

Colonel Katja Tersch, 49, from the State Criminal Police Office reported that the police are having trouble identifying the culprit due to the lack of information on his physical appearance.

She said: “The hot lead is not there.”

The investigation is ongoing.