They, however, held the MLA's brother Baijanth, already arrested in this case, responsible.
A five-member team declared Mahto innocent after questioning at least 50 villagers, including family members of the victim, who "denied" any role of the MLA in the incident, but accused his brother and others, SP Jitendra Singh told reporters here.
The team comprised DSP, SDPO, an inspector-rank police official and officers-in-charge of Nawadih and Chandrapura police stations, he said.
The same day Mahto's brother, Baijnath was arrested and the six others, who surrendered were sent to judicial custody.
The SP had said the family in the initial FIR had accused nine persons, including the MLA, for allegedly convening a 'jan adalat (people's court)' at Narah village where Santosh Pandey (22) was beaten up over a love affair. He later died in hospital.