Upon visiting Wilson Pillco at his home, police spotted men's Reebok sneakers that looked a similar size to the footprint discovered in the bathroom. The shoes turned out to belong to his brother, Diego Pillco, who had illegally immigrated from Ecuador and had also been working on the construction project. At first, Diego was hesitant to talk, but he eventually confessed. He told police that Adrienne Shelly had confronted him regarding noise from the construction and that she had threatened to call the police. Fearing the worst as an immigrant, Diego followed Shelly to her apartment, where he pushed her and she knocked her head. He then assumed Shelly was dead and staged a suicide to shift the blame.
However, the version of the story Diego originally told the police turned out to be false. He later revealed the truth: Shelly caught him sneaking into the apartment and taking money from her purse before saying she would call the police. Terrified of being deported back to Ecuador, he attacked Shelly inside the apartment. During Diego's initial bail hearing after the arrest, Assistant District Attorney Marit Delozier said (via CBS News), "He said he fought with the victim, tied a sheet around her neck and dragged her to the bathroom and hung her from the shower rod."
After Diego Pillco's confession, everything fell into place, including the fact he was able to create such an intricate knot due to his experience with tying pigs in Ecuador. Per The Guardian, it was later revealed that neck compression was Adrienne Shelly's official cause of death, which could have been from either the strangling or the staged hanging.
