Dying declaration is an important piece of evidence under Section 32(2) of the Indian Evidence Act. The court can convict the accused on the sole evidence of dying declaration if it seems true. It is the duty of the prosecution to prove the dying declaration of the deceased.
You said that there are contradictions in the dying declaration. If there are more dying declarations than one then it may have some contradions and the court will check the veracity of dying declarations. In case there is only one dying declaration then contradion is not possible.
In the first sceneration the court may discard the dying declaration if the contradictions are major and significant. The court will reject the dying declaration and cannot convict the accused on such a dying declaration. Thus, the conviction will base upon the proof of other criminating evidence.
In case of minor contradictions the court will not reject the dying declaration. Because, the witness has the tendency to refine his statement.
Contradiction between dying declaration and other evidence
A dying declaration becomes contradictory if it does not get corroboration from the other independent evidence like post mortem report, evidence of eye witness etc. In this situation the court will not rely on the dying declaration but appreciate other evidence.
This is not a rule that the court will acquit the accused on the suspicious dying declaration. Whereas, the court will convict the accused if the prosecution has successfully proved the culpability of the accused. The prosecution can prove the guilt of your brother by other evidence. So, I can’t say that the court will acquit your brother because the dying declaration remains disproved. There is a good chance that the court will convict the accused on the evidence other than dying declaration.