Believe you are a defacto complainant in this case?
Why did you not ask your father about he turning hostile witness?
The other eye witness cannot turn hostile on his own unless the police and the public prosecutor have colluded with the accused side, if you suspect foul play then you can very well make a complaint in this regard to court vigilance department with evidence and seek for investigation.
Before that you obtain certified copies of the witness deposition and also the witness original statement and enclose them as documentary evidence to your complaint with the high court vigilance department.
You may take the assistance from a local lawyer and proceed as suggested.