He had gone to pluck temple flowers in the camp's vicinity when he was shot dead, said Police sources in Batticaloa.
Sinnavan has been attached to the Manmunai STF camp for more than five years.
This camp is on the eastern shore of the Batticaloa lagoon at the ferry to Kokkaddicholai, a large village in the western hinterland which is under the control of the Liberation Tigers.
The Manmunai ferry is about 10 kilometers south of Batticaloa town. The STF has a camp and checkpoint here. The ferry carries the greater part of the traffic to and from the western shore (Paduvaankarai).
People passing through the ferry checkpoint, according to sources in Batticaloa, were screened by Sinnavan.
There have been regular complaints from civilians that he was engaged in extortion.
Local human rights activists have held him responsible for torturing civilians during cordon and search operations by the STF in nearby villages and during detention at the Manmunai STF camp.
The STF, however, claims that he was very effective in preventing LTTE infiltration into the government controlled parts of Batticaloa through the Manmunai ferry point.
The Liberation Tigers, according to the STF, had made several unsuccessful attempts to assassinate Sinnavan.
A miniature bomb concealed in a cigarette blew up on his face once but failed to kill him.
Sinnavan was a member of the Eelam People's Revolutionary Front (EPRLF) and worked with the Indian army from 1987 to 1990.
However it was widley believed by the public passing through Manmunai that he was a TELO member.
Sources in Batticaloa said he was one of the EPRLF cadres who led the conscription drive by the EPRLF in Batticaloa for the Tamil National Army which was raised under the Indian Peace Keeping Force in 1989.
The conscription made the EPRLF extremely unpopular in the Tamil areas of the island.
Sinnavan followed the Indian army to India when it was pulled out from Sri Lanka in early 1990.
He returned, according to local EPRLF sources, in early 1991 after the Sri Lankan army had moved into and consolidated its position in the Batticaloa town and the eastern coastal areas of the district.
Since then he has been working with the army and later with the STF they said. Sinnavan is from the village of Kokkaddicholai.
