On September 19, 1970, Joseph Baldi was looking for an apartment in Jamaica, New York, when he decided to sneak into a place through a window at 144-96 88th Avenue. Inside, he unexpectedly encountered 23-year-old Areti Koularmanis, a Greek-Canadian visiting her in-laws with her kids. In a panic, Baldi attacked her with a knife to keep her quiet. Although she managed to alert her husband, she collapsed and later died in the hospital from her injuries. Baldi fled the scene, and despite extensive efforts, the police could not identify him.

Baldi's crimes continued, and he regularly targeted ground-floor apartments. On September 5, 1971, after a witness reported seeing him climb through a window, police officers John Hamberger and Frank Mobileo responded. Confronted by the officers, Baldi pulled out a gun and tried to shoot, but it misfired. He was then arrested and found in possession of stolen items, leading to charges of attempted murder, burglary, theft, and illegal weapon possession.

Baldi, who had a history of mental illness, was sent to Mid-Hudson Psychiatric Hospital but was mistakenly released due to a paperwork error. He quickly resumed his criminal activities, escalating in violence. In March, he broke into another apartment and murdered 17-year-old Camille Perniola while she slept. In April, he attacked 21-year-old Clara Toriello, stabbing her multiple times. His last known crime occurred in June when he fatally stabbed 15-year-old Deborah Januszko. She managed to tell her parents she had been stabbed before succumbing to her injuries.

After some of Januszko's classmates reported being stalked by a man fitting Baldi's description, he was apprehended by detectives from the Queens Homicide Squad. He soon confessed to harming Januszko and was linked to other crimes.

At his trial for the attempted murder of Officer Hamberger, Baldi pleaded not guilty by reason of insanity. However, a psychiatrist testified that Baldi was aware of his actions during the attack. He was convicted and sentenced to 25 years in prison. Despite being barred from using reenactments of his murders in his defense, a confession tape where Baldi admitted to four murders was played in court. Although some charges were dismissed on procedural grounds, Baldi was convicted for the murder of Januszko and received a 25-year-to-life sentence, which he served at Sing Sing until his death in 2009.

Baldi's release from a mental hospital as a "model inmate" sparked widespread controversy, especially since he continued his criminal activities after release.