The woman who fatally stabbed one person and critically injured another in Times Square on Monday had a long history of mental health struggles, according to her brother.

Pamela Cisneros, 49, had been diagnosed with a mental health condition and previously attempted suicide around age 19, her brother, Patrick Peralta, told The Post. Peralta believes his sister may have been bipolar, though he is unsure of the exact diagnosis. He stated she had been receiving monthly injections for treatment and speculated that stopping these injections might have contributed to her actions.

Peralta, 59, expressed shock at the incident, stating that Cisneros had never displayed aggressive or violent behavior. He learned about the attack through news reports and initially dismissed them as "typical New York crap" until he saw photographs of his sister involved in the confrontation.

The incident occurred near West 41st Street and Seventh Avenue around 4:30 p.m. Monday. Video footage shows NYPD officers confronting Cisneros, who was still holding two knives. Officers first attempted to subdue her with stun guns, but she charged at them, leading to her being shot. She later died from her injuries at Bellevue Hospital.

Peralta last saw his sister in August during their stepfather's birthday celebration. He noted that she had recently stopped visiting their mother regularly, but when he and his family called, she assured them she was fine on Saturday, just days before the attack.

Photo of two knives recovered at a crime scene, held up by an officer.