NEW YORK

Police had tens of hours of security-camera footage, a rope to test for DNA and extensive interviews with possible witnesses

But nearly two months after someone hung a noose on a Black Columbia University professor’s office door, police say they have no suspects in the apparent hate crime that shook the Ivy League campus.

A separate case involving a Jewish professor and a swastika at the same graduate school of education also remains unsolved. Both incidents were part of a recent surge in reports of hate crimes across the city, police say.

Police had held out hope that an exhaustive review of the surveillance images would help break the case of the noose, found Oct. 9 at Columbia’s Teachers College. But the analysis yielded “no relevant information,” Police Commissioner Raymond Kelly told reporters Friday following a promotion ceremony.

Nor have any promising leads sprung from interviews of faculty members and students or DNA testing on the 4-foot length of rope, officials said.

In recent weeks, Teachers College administrators have organized campus forums on race to try to soothe “bruised feelings” while awaiting an arrest, said college spokesman Joe Levine.

“You don’t like to think that person’s out there, but I think the police are doing everything they can,” Levine said.

A telephone message left Friday with the apparent target of the noose, Dr. Madonna Constantine, was not immediately returned. Constantine, 44, is an education and psychology professor who has written extensively about race.

Nooses are racially charged symbols of lynchings in the Old South and have appeared in a number of recent incidents around the country. The discovery of the noose at Teachers College sparked outrage among students, faculty and administrators, and Constantine denounced it the next day at a raucous rally.

Then, on Oct. 31, Teachers College Dr. Elizabeth Midlarsky found a swastika painted on her office door. Police said Friday there were still no suspects in that case.