Cocaine-Related Murder Claim 'False': Father
The father of  missing Australian student Brendan Dobbins has labelled as false a claim his son was murdered in Costa Rica after a cocaine deal went wrong.

The claim came as Costa Rican police matched Brendan's dental records with those of a body found 3km from Tamarindo beach, where the 24-year-old RMIT University student vanished on March 4.

He was studying in the US on an exchange program, and travelled to Costa Rica with Australian and US friends.

Brendan's father, Brian Dobbins, confirmed  the family had hired Jose Antonio Rojas to investigate his son's disappearance. But he was fired on April 23 after he produced false information, Mr Dobbins said.

"Effectively this person was engaged by us for two to three days," he said.

"But he generated false information which caused the Costa Rican authorities to use a huge amount of resources to dig looking for a non-existent body on the beach."

Mr Rojas told that Brendan Dobbins had been murdered following a cocaine deal that went wrong.

"We're talking about an organized gang in the 13th region of Tamarindo dedicating themselves to trafficking drugs," he said.

Brendan Dobbins was hit over the head with a bottle and then gunned down after a drug deal turned sour, he told Nine.

"This is the gun ... it wasn't buried, it had three bullets in it and was dumped on a side path," Mr Rojas said.

Mr Dobbins said he had received information from the Australian Department of Foreign Affairs and Trade (DFAT)  indicating further DNA testing was needed to ascertain whether the remains uncovered by fisherman at Playa Langosta beach last week were those of his son.

"There is an indication there was a (dental records) match but it is not conclusive because additional tests are required," he said.

Mr Dobbins said the additional DNA testing could take months.

"It is obviously difficult to cope with the uncertainty," he said.

Mr Dobbins said reports he was preparing to fly to Costa Rica to provide a blood sample were wrong, and he was yet to consider whether he would fly back.