“She talked about leaving the country,” Mr. Felder said.

He said that a judge recently told her she could not take her son to Europe, as she had wanted. According to the law enforcement official, it appeared that Ms. Nicolai had been asked on Thursday to relinquish her son’s passport.

Image Stephanie Nicolai in 2006. Credit... Brad Barket/Getty Images

Though Mr. Felder said he did not represent Ms. Nicolai in recent legal proceedings, he believed she had unrealistic expectations about her divorce and custody options.

“I felt she needed help in a different area,” Mr. Felder said. “I’d been her friend for 20 years.”

This week, Mr. Felder said, a notice came addressed to him and his former client from the city’s child welfare agency. It appeared that she had made an inquiry with the agency to see if there were any open investigations, he said, but there were none. Such inquiries to the agency, the Administration for Children’s Services, are common in contentious divorces where a parent makes a claim against another.

Sanford A. Rubenstein, a lawyer who represented Ms. Nicolai in a case against the Police Department, recalled how a civil jury in Manhattan ruled in 2012 that she had been the victim of excessive force and awarded her $1.2 million — a sum a judge later reduced around $400,000. Four years later, Mr. Rubenstein said, the Police Department granted her a gun permit after initially denying it.

“She had felt at the time that the actions of the police were in part as a result of her being successful in the lawsuit against them,” Mr. Rubenstein said. He said she called him often as recently as “a few months ago,” to speak about her businesses or “the matrimonial matter or the custody matter” that she was confronting. He said he believed she was separated from her husband.

“She really loved that boy,” Mr. Rubenstein said of the 7-year-old. “During the trial, she would bring the little boy with her to court every day and the judge gave her a separate room to sit in with the child. She was inseparable from that child.”