Debevoise & Plimpton corporate partner Stephen R. Hertz, 55, died Friday evening after falling from his Upper West Side apartment in an apparent suicide, New York City police and fire officials said.

Police were called shortly after 9 p.m. Around that time, the building manager of Hertz’s apartment at 105th Street and Central Park West found his body in a nearby tree. Hertz was dead by the time officials responded, a fire department spokesman said.

Earlier that evening, Hertz e-mailed a suicide note to his ex-wife, who forwarded it to a psychiatrist, the New York Post reported. The psychiatrist then called 911.

Hertz had been a member of Debevoise’s mergers & acquisitions and private equity practice groups and worked for the firm since graduating from law school in 1985. He had been at work on Friday, the firm said.

“We are shocked and deeply saddened by the passing of our partner and friend Steve Hertz,” the firm said in a statement. “Steve was an exceptionally warm and caring person, extraordinarily dedicated to our clients, and generous to his colleagues. He will be profoundly missed.”

His clients included public and private companies including Landstar System, a transportation services and logistics firm, and Cambrex, a life sciences firm. He has also represented private equity companies such as Stone Point Capital and HarbourVest Partners.

Hertz was a graduate of Middlebury College and the University of Chicago Law School. He was admitted to the New York state bar in 1987.

Funeral arrangements have not yet been finalized.