In villages, sometimes aggressor party gets kille and real victim who tried to save himself is prosecuted as murderer.
In such a case, only defending oneself in trial is not enough. Sec.96 to 98 and 100 to 106 of IPC apply.
It is duty of accused to bring on record evidence to justify Private Defence, 1) By giving deposition on oath 2) Or through cross-examination of witnesses.
2012(5) SCALE 52 on page 57 para 13 Arjun’s Case