"I understand your frustration with the ongoing police investigation and the problems you encountered at the early stages of the case".

"Whilst we cannot interfere with the investigation, British officials have continually worked to ensure the case is investigated thoroughly. I understand they have raised Scarlett's case with a number of Indian officials," Brown said in a letter written to Mackeown dated May 9.

Scarlett's bruised body was found on Goa's popular Anjuna Beach on Februry 18. After initial goof-up, Goa police have arrested two locals for their involvement in drugging, raping and leaving Scarlett to die on the shore.

Goa government, which was in the earlier stages reluctant to handover the case to CBI, has finally agreed to do so in the wake of intense media and diplomatic pressure.

"I was shocked and saddened to learn of Scarlett's death in February and cannot imagine the distress your family continues to suffer. May I offer you my sincerest condolences at what must be an extremely difficult time," the letter says.

The Prime Minister has said that on April 7, the British High Commissioner in New Delhi had discussed the case with Indian Foreign Minister and asked for clarification on the progress of the investigation and for details of action that has been taken so far.