An un detected case of ligature strangulation

This occurred in the year 1988-89. A body involved in pattambi policestation crime & recovered from a temple pond in pattambi taluk was brought for autopsy. The hands & feet were tied separately with coir rope.The manner in which the hands & feet were tied could not be tied by the person himself. There are instances in history where a person tied his hands & feet & jumped into water.Signs of submersion could be made out& the body was in a very early state of decomposition. Examination revealed an oblique ligature mark oblique&across the middle of thyroid cartilage& it was having a pattern to that of a rope(7-8cm) Underneath there was infiltration of left sublingual gland. The other neck structures were free of injuries. There were no other injuries on the body. Viscera & blood preserved turned out to be -ve for poisoning.
I used to discuss cases with my seniors at that time & also till my retirement & after that also. This particular case was presented before my HODat that time & my opinion " The pm findings were consistent with death due to ligature strangulation" was acceptable to him. Later on when the Investigating officer was not able to proove the case; the same HOD became hostile towards me. & he answered the questioner put forward by the investigating officer. It went to such an extend that he even proclaimed to tarnish my image. He gave a statement that Iam an inexperienced person & donot know anything. In a stage of decomposition the neck creases will be misinterpreted as ligature mark.At the end he quoted " possibility of death due to ligature strangulation cold not be ruled out." !!??
Later on the case was submitted before the Medico-legal advisor to kerala police & he stated that the ligature mark!! Whether patterned? Imay ask now. At the end of his statement he opined that theligature mark was there& it could have produced by the person tying a rope around the neck & the other end of the rope was tied around a granite stone & the person tied his hands & feet & jumped into water. Using a motor pump the police drained the water from the pond & they were not able to locate the rope,stone etc.
Till this date nothing is known about the case.
Iam in darkness with regard to the strange behaviour of my HOD. Now we are in good terms.
dr.n.rajaram