The best thing about negative karma is that it can be purified. The Buddhist approach to negative deeds avoids the concept of guilt and sin and uses compassion, remorse and redemption as ways to forgive the past and courageously press forth on our spiritual path towards awakening.

This video explains some of the methods in Buddhism for purifying our past negative karma and introduces some key historical figures who have purified very heavy negative karma and gone on to achieve extraordinary levels of spiritual attainment in one lifetime.
 
 
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