Michael Peterson was accused of killing his wife, Kathleen, though he claims he had nothing to do with her death. He was convicted of murder and sentenced to life in prison, but released in 2017 after making a plea deal.

This was not the first person Peterson cared about that was found dead at the bottom of a stairway. In the video above, he explains what happened to a good friend of his in Germany in 1985 – and what happened when the woman’s body was exhumed after Kathleen’s death.

On Monday, Peterson explains the mysterious circumstances surrounding Kathleen’s death. And on Tuesday, hear about a bizarre theory that may hold the key to what really happened to Kathleen. Check here to see where you can watch.