There is no doubt that killing a human being is one of the most
dangerous major sins. But we read in the Holy Qur'an in chapter 39 Surah Zomar, verse 53 : "O My servants who have transgressed themselves
(by committing evil deeds and major sins) despair not of the mercy of
Allah . Verily Allah forgives all the sins. Truly He is oft
forgiving, most merciful'.
Any sinner who sincerely repents and seeks forgiveness, Allah (SWT)
who knows what is in the hearts has mentioned in the Holy Qur'an that
He forgives all sins. That does not mean wasting the rights of the
victims' family which is ordained in Islam. But as far as the
relationship between the sinner and Allah (SWT) is concerned, Allah (SWT)
forgives all those who repent sincerely.