First a case of drowning, then rape and murder and now drug overdose -- the list of theories surrounding the death of British tourist Scarlette Keeling is endless. And even though the Goa [Images] police claims to have cracked the, doubts still linger on whether the cops have hushed up this case further.

If one looks closely at the manner in which the investigation has been conducted, it raises several doubts.

The prime witness in the case, Mike Mannion aka Masala, is yet to testify and the Goa police are still on the lookout for him. No murder case is complete without the testimony of a witness unless the police are planning to go ahead with the trial based on circumstantial evidence.

At the moment, it seems unlikely that the police may fight the case on the basis of a circumstantial evidence, as the mother of the victim has been raising several doubts about the arrest of the two persons, Samson D'Souza and Placido Carvalho.

Both Scarlette's mother, Fiona, and her lawyer, Vikram Verma, claim that the two persons arrested are 'small fries' and there is much more to the case.

Has the Goa police come to the conclusion based on the interrogations conducted on Samson and Carvalho? Well if this is the case, then this can easily be challenged by the accused in the court of law, as a confession before the police is not valid under law.

Another question being raised is with regard to the scientific tests. There are so many indiscrepancies in the versions given out by the cops that this is surely going to raise a doubt in the mind of the court. The samples of viscera were first ordered to be sent to the Hyderabad Forensic Sciences Laboratory, but were later sent to Mumbai.

Apparently, the Hyderabad FSL told the Goa police in the last week of February that they could not conduct a test for another two years as their hands were full. Despite this communication, the Goa police took its own time and eventually decided to send the viscera to Mumbai only in the first week of March.

It would be interesting to see what the result of the test in Mumbai would state. Normally there is every chance of damage to the viscera in case it is kept for a long time, according to Forensic Science experts.

Another aspect that remains unexplained is the wounds on Scarlette's body. The Goa police first booked a case of rape against Samson D'souza after he claimed that he had consensual sex with Scarlette. Now the police say that she was sexually assaulted by Carvalho and could have died of drug over dose later.

However, there is no explanation as to why there were wounds on the 15-year-old's body. The police had said after the first autopsy report that there were six wounds on the body, but after the second autopsy report it was reported that there were close to 50 ante and post mortem wounds.

Another strange aspect to the investigation is regarding Carvalho. He was picked up a couple of days back and then released. Now he has been made out to be the prime suspect in the case. The anticipatory bail applications filed by both Carvalho and another suspect, Julio Lobo, give more insights into the case.

Carvalho had said that Scarlette was seen with a man by the name Murli before coming to the shack at the popular Anjuna beach. Samson had spoken about a girl, named Ruby, of Spanish origin. He had said that Scarlette was supposed to go out with Ruby, but later he realised that she was not with him.

Have the police gone into these angles? Suspects may give a thousand versions to defend themselves, but that does not mean that the police can turn a blind eye to it. Scarlette's mother says that she will not rest unless and until the real truth prevails. She suspects that it is a nexus between the police and the big names that are involved in the case.