Complex sentence: Between late 2005-2006 Hwang came under fire for a series of misconducts, first related to his work prior to Snuppy; the claim that he had successfully cloned a human embryo.
Split into simpler sentences: Between late 2005-2006 Hwang was accused of a series of misconducts. The first allegations related to his work prior to Snuppy; the claim that he had successfully cloned a human embryo.