Investigators are still working to determine who sent a bomb to the home of a Medical School faculty member last month, local authorities said yesterday.

Dr. Paul A. Rosenberg, an assistant professor of neurology at the Medical School who works at Children's Hospital, unwittingly averted the detonation of two six-inch pipe bombs contained in a package sent to his home in Newton, the Boston Globe reported.

On December 19, after Rosenberg and his wife returned from a vacation, he cut open the top of the box with a knife rather than opening the flaps, which would have activated the bombs, according to the Globe. When he saw a metal cylinder and wires in the package, he and his wife ran out of the house and he called the police.

The state fire marshal's office disarmed both of the bombs. Police told the Globe that the explosion "would have killed anyone in the immediate vicinity."

Authorities have been unable to come up with new information since the incident.

"It's still an active investigation," saidGroup Supervisor John Dowd of the Bureau ofAlcohol, Tobacco and Firearms in Boston.

Lt. Robert McDonald of the Newton PoliceDepartment, which is assisting in theinvestigation, said investigators are still tryingto lift fingerprints and analyze the compositionof the bomb. But the investigators "don't have anysuspects to date."

Rosenberg, contacted at his office yesterday,said "There's not much we can say" about theincident. Kristi Kienholz, a spokesperson atChildren's Hospital, said Rosenberg could notcomment further because of the ongoinginvestigation.

The Postal Inspection Service, the organizationheading the investigation, could not be reachedfor comment yesterday