India, Aug. 18 -- Shocking new details have emerged amid an investigation into a "mystery house" in Philadelphia's Olney neighborhood. Eugene Horsch's house is now in focus, with "graphic" videos being recovered by police. Meanwhile, serial killer claims continue to surface on social media.

During the probe, investigators found evidence suggesting an attempt to grow or produce narcotics. Among several items seized was a piece of writing about serial killer Ted Bundy that referenced zip ties and a drum, a source familiar with the investigation told NBC10. The note even mentioned killings and "trash that needs to go."

It remains unclear who wrote the piece. However, Horsch's attorney suggested in an earlier conversation that the author wa...