Gujarat BJP leader Chhabil Patel and five others, including his son, have been made suspects in an FIR lodged by the Railway Police today in the murder of former BJP lawmaker Jayanti Bhanushali.
Mr Bhanushali was shot dead in a moving train in Gujarat on Tuesday.
The police, however, said none of them has been made an "accused" yet, and no one has been arrested so far.
The FIR is based on a complaint by the BJP leader's nephew Sunil Bhanushali, who accused his uncle's rival Chhabil Patel of orchestrating the murder.
Other suspects were include Mr Patel's son Siddharth Patel, Manisha Goswami, Jayanti Thakkar, Umesh Parmar and Surjit Bhau.
"These six persons have been shown only as suspects, not as accused. The FIR was lodged on the complaint given by Sunil Bhanushali," Police sub-inspector CS Saundarva said.
Mr Bhanushali represented Abdasa Assembly constituency in Kutch from 2007 to 2012. Chhabil Patel, a Congress candidate then, defeated him in the 2012 Assembly elections.
After two years, Mr Patel joined the BJP but lost the resultant by-poll for the seat in 2014. In 2017, the party chose Mr Patel over Mr Bhanushali for the Abdasa seat, but he lost to a Congress candidate.
Mr Bhanushali's nephew alleged that Mr Patel held his uncle responsible for his defeat in 2014 and 2017 and held a grudge against him.
He also alleged that to end Jayanti Bhanushali's political career, Chhabil Patel and others made a CD which showed his uncle in a compromising position with a woman.
When Mr Bhanushali refused to retire from political life as allegedly demanded by Mr Patel, he hatched the murder conspiracy, the complaint said.
Minister of State for Home Pradeepsinh Jadeja said a seven-member SIT is probing the case on "war footing" and has roped in fingerprint experts and forensic as well as ballistic experts to aid detection.
"The government has taken this incident very seriously. Notwithstanding the party association, we will take action against anyone found guilty of the crime," Mr Jadeja said.
Jayanti Bhanushali had stepped down as Gujarat BJP vice-president in July last year after a woman accused him of rape. The High Court had quashed the case after she withdrew the complaint.