How did Haridatt die?

Haridatt's death (March 15, 2012)
http://youtu.be/8kRpYDAlAsw

Haridatt PG, Additional SP who investigated and chargesheeted the Sampath custody murder case against Kerala police officers, was found hanging from a rafter in his old house. Allegedly he used a cycle chain to hang himself.

A suicide note was found on his body.

Did Haridatt commit suicide or was he murdered?
The suspicious circumstances surrounding his death are:

• There were threats to his life and he had sought protection from the Court and from the police
• A cycle chain is not used normally used for hanging and is usually associated with criminal gangs as their weapon.
• The suicide note does not indicate that he is taking his life, but makes accusations against four persons (two CBI officers), an advocate and the Chief Judicial Magistrate. 
• Haridatt was a strong person and was very happily married.
• If he was unhappy with CBI, he could have sought voluntary retirement.

Was he abducted, forced to write the note and then silenced and hung using the cycle chain while he was unconscious and alive?

An impartial and thorough probe is required to ascertain the facts and circumstances of Haridatt's death.

The suspicious suicide note

F.I.R. Mar 16