Tafsir of Al-Baqarah 2:192

(But if they cease) from disbelief by repenting from it, as narrated from Mujahid and others, or from disbelief and fighting, as has been said—due to the contextual indicator of both matters being mentioned—(then indeed, Allah is Forgiving, Merciful) (192), for He will forgive them for what has passed.

It is inferred from this in al-Bahr that the repentance of an intentional murderer is accepted, since disbelief is a greater sin than murder, and He, Glory be to Him, has informed that He accepts repentance from it.