Scarlett died after her head was held under water

New medical report backs up family's claim that the teenager was murdered

British teenager Scarlett Keeling died after her head was held under water, according to the family's lawyer who revealed that a new medical report will add weight to evidence suggesting she was murdered, contrary to initial claims by the police in Goa.

Local reports say a new forensic report by Goa Medical College into the death of the 15-year-old contradicts the most recent theory of the Goa police, that Scarlett was drugged and raped before drowning on a beach, and may lend weight to the accusations of corruption that her mother, Fiona MacKeown, has levelled at police and local authorities.

The teenager's body was found semi-naked on Anjuna beach in Goa on 19 February. Police first claimed that Scarlett, from Bideford, Devon, drowned when drunk. It was only after campaigning on the part of Scarlett's mother that a second post-mortem took place, which revealed that the teenager had actually been raped and murdered.

"I want the police brought to justice. They have interfered with the evidence – this is proof," Mrs MacKeown told Sky News yesterday. "I'm just horrified that the police are still covering up my daughter's death. Who are they covering for? It must be someone very important."

Two men have been arrested and remanded in custody in connection with the crime. Police claim that barman Samson d'Souza, 28, has confessed to raping and murdering Scarlett, along with alleged drug dealer Placido Carvalho. The family was on a six-month holiday in India when Scarlett was killed. The teenager was staying with her 25-year-old boyfriend – local tour guide Julio Lobo – at the time of her death, while Mrs MacKeown, her partner and six other children, travelled around the region. Mrs MacKeown has since appeared before an Indian court on charges of negligence.

Mrs MacKeown has claimed that the state's home minister, Ravi Naik, and the director general of police, B S Brar, covered up her daughter's murder to protect powerful drug dealers.

The new forensic evidence comes days after the results of another post-mortem which police claimed revealed a cocktail of cocaine, morphine and alcohol in the girl's blood. "The narcotic drugs and alcohol form a part of the chain of events that included rape and drowning of a girl who could not defend herself," the Goa police chief, Kishen Kumar, said on Thursday.