A University of Pennsylvania law student couldn't shake his paranoid suspicion that his two neighbors, Drexel University graduate students, were foreign spies sent to work on some sort of a terrorism plot, police said.

His anger-laced curiosity grew after he approached the roommates, both Indian-born bio-engineering majors, during a seemingly friendly conversation yesterday morning as the three men left the apartment building at 43rd near Pine streets before class, said cops.

At about 12:30 p.m, the 31-year-old Korean-American law student returned home, took out his legal Glock-9, and knocked on his neighbors' front door.

The 22-year-old Drexel student, the only one inside, ignored the pounding. The Penn student's anger exploded as he fired about 15 shots into the apartment's door, three of which sliced through the door's lock.

The wannabe lawyer, whose name wasn't released, left the building as the graduate student hid in a bedroom, police said.

"It is a strange case," said Lt. John Walker of Southwest detectives.

Another neighbor called 911, and officers found the 22-year-old Drexel student still cowering inside the apartment, said police.

Minutes later, the law student returned to the building, thinking he had done nothing wrong. Cops quickly nabbed him, police said, and held him for questioning.

Police said they expected the law student to be charged in the next 24 hours, and that investigators will notify police terrorism officials about the reason behind the shooting. His name has not been released.

The Penn student "is accusing [the Drexel students] of something with no basis" other that they are from India, and "the curriculum" - bio-engineering - they are studying at Drexel.

Meanwhile, Drexel moved out all its students who resided inside the three story rowhouse building yesterday, arguing that the residence was no longer "secure," Walker said.

Last night, a group of Indian-American fraternity brothers, who attend University of the Sciences in Philadelphia, stood outside their frat house and gawked at the swarm of reporters casing Pine Street.

"I am used to muggings around here," said sophomore Arpit Shah, 19, a member of Phi Kappa Psi fraternity.

But "spies - that is out of left field. Spies in West Philly - that is ridiculous."

Shah's frat brother, Bhabin Patel, agreed.

"You'd think a law student would be smarter than that," Patel, 21, said. *