Panaji, Feb 3 (IANS) In a new twist to British teenager Scarlett Keeling's sexual assault and culpable homicide case, a prosecutor appearing for the CBI Thursday said he wanted to withdraw from the trial as it was taking "too long".

Prosecutor S.R. Rivonkar has written to the Central Bureau of Investigation (CBI), the investigating agency in the case, that he could not continue to appear in the case.

"The Scarlett case will go on for a long time. It was going at a regular pace, but for some time now the hearings have been irregular. It is taking too long. I cannot give so much time to this case as I have a lot of matters pending in the high court," Rivonkar told reporters here, after sending the letter to the CBI.

"A regular public prosecutor will be handling the case," said Rivonkar, who was specially appointed by the CBI as a prosecution lawyer in the high profile case.

The trial in the case began in April last year and statements of 15 witnesses, including Scarlett's mother Fiona Mackeown, have been recorded by the children's court, the designated authority in Goa to try crimes related to minors. In all, 72 witnesses are to be examined in the case.

Scarlett Keeling, 15, was sexually assaulted and left to die at Anjuna beach Feb 18, 2008, by two beach shack workers. The police had initially dismissed the case as death due to drowning.

The victim's mother started a high-profile campaign for justice, which caught the attention of the media across the world.