I would be hesitant to believe any such rumors about the Stormtrooper Corps. They were the target of many Rebellion/New Republic slander campaigns.

Not a historian but I've done some independent reading on this matter and I think I can answer your question.

The Stormtrooper Corps were one of the military branches of the Galactic Empire's Armed Forces, separate from both the Imperial Army and Imperial Navy. They had their own command structures, traditions, customs and operations, and answered directly to Herr Palpatine himself. They were the elite shocktroopers of the Galactic Empire, fighting in a number of battles against the Rebel Alliance, such as the Battle of Hoth and the Battle of Endor. They served alongside the Imperial Army and Imperial Navy forces in these battles, demonstrating no more or no less regard for the conduct of warfare than their peers. For example, there is documented evidence of members of the Stormtrooper Corps that remained behind on Endor to help with relief efforts for the Rebel-orchestrated Endor Genocide. When the Galactic Civil War came to an end, however, elements of the Imperial Army and Imperial Navy which wished to inundate themselves with the New Republic leadership concocted a fabrication, with the complicity of said leadership, to discredit the Stormtrooper Corps. So, as /u/jetshockeyfan said, you should be hesitant to believe such rumours about the SC. They were subject to a hatchet job by the New Republic government, with galactic media discrediting them. Stormtrooper Corps relief efforts, such as the conservation effort on Felucia, to save the endangered Acklay, were whitewashed, and media stories about these relief efforts were edited by the New Republic government, to remove any mention of the benevolent acts of the Stormtrooper Corps. In fact, you could conclude that, rather than being responsible for warcrimes, the Stormtrooper Corps actually attempted to do the opposite, but were slandered by the Imperial Army, Imperial Navy and the New Republic.