Police stumbled upon a bomb-making factory Sunday in the home of a Columbia professor who specializes in the spread of infectious disease - and are investigating whether he and his roommate have terror ties.

Cops evacuated the Brooklyn Heights neighborhood around the Remsen St. home of Michael Clatts, a medical anthropologist, after finding seven pipe bombs fitted with fuses in his flat, police sources said.

The frightening cache was discovered almost by accident - Ivaylo Ivanov, the man living with Clatts, accidentally shot off the tip of his left index finger and sought police help in the street about 1:15 a.m.

When investigators went to  the 37-year-old Ivanov's apartment, they found the bombs, already capped on both ends and filled with powder. One of the pipe bombs was inserted into a Nerf football, cops said.

A 9-mm. handgun, two ammunition magazines, a 12-gauge shotgun, silencers, a bulletproof vest, a crossbow and bomb-making equipment, including a drill and threading machine that could be used to make pipe bombs, were also recovered, cops said.

Investigators with the NYPD-FBI were questioning Ivanov, a native of Bulgaria, to determine whether he had any terrorism or Russian Mafia connections, a source told the Daily News.

"Russian Mafia aren't fazed by getting a fingertip shot off - and they certainly don't go to the cops for help," the source said.

Neither man so far has popped up on any foreign criminal watch list or is a known member of an organized crime ring, sources said.

Sunday night, police were seeking additional search warrants, possibly for computers, other electronic devices and papers and books.

Ivanov was charged with criminal possession of a weapon, unlawful wearing of a body vest and reporting a false incident, cops said. He was expected to be arraigned this morning.

Police were also looking to question Clatts, 50, the Columbia University instructor living with Ivanov, a source told The News.

Alan Brasunas, a co-op board member at the 58 Remsen St. brownstone, confirmed Clatts owned the apartment and lived there with Ivanov.

"One has to assume Michael must have seen something at one point," Brasunas said. "It's not a huge apartment."

He said he interviewed Clatts before he was allowed to buy the fourth-floor unit.

"We obviously have concerns about both people," said Brasunas, who called the professor a "quiet, reserved person."