Months before Martial Simon pushed Michelle Go to her death in front of a subway train, his mind had been seized by an unusual toothache.

Simon was confined at the time to the Bronx Psychiatric Center, a state hospital. A nurse offered to connect him with a dentist, but he refused. The dentist was working with the FBI, which was using satellites to loosen his teeth, he said.

Despite Simon’s tenuous grasp on reality, the hospital discharged him a few weeks later, in July 2021. He had been hospitalized for five months. Workers escorted him to an apartment building in the Bronx, where he could live with on-site services. They left him with a 30-day supply of medication and a next-day appointment with a psychiatrist.

He never showed. In all, he spent hardly two hours in his new home. He left only a trace of his presence: a brown paper bag stuffed with his medications.