Complex sentence: Some scholars (e.g. Loren Graham) have speculated that his death may have been a suicide, because Bogdanov wrote a highly nervous political letter shortly beforehand, while others attribute it to blood type incompatibility, which was poorly understood at the time.
Split into simpler sentences: Some scholars (e.g. Loren Graham) have speculated that his death may have been a suicide, because Bogdanov wrote a highly nervous political letter shortly beforehand. Others, however, attribute his death to blood type incompatibility, which was poorly understood at the time.