Federal authorities investigating the May 21 bombing at the Yale Law School have impaneled a grand jury to collect evidence on former or current employees and students who may hold a grudge against the school, The Hartford Courant reported June 21.

The Courant, which did not identify its sources, said the grand jury was convened at least three weeks ago. No one was injured in the bombing, which destroyed a wall between two classrooms and damaged some artwork.

Benjamin Johnson, the University of Wisconsin-Madison student who was convicted last year of stealing $2.5 million in artifacts from Yale’s Beinecke Rare Book and Manuscript Library, was arrested in connection with the bombing probe on June 4 after police searched his home.

Johnson, 23, was released six days later.

Delcie Thibault, a spokesperson for the United States Attorney’s Office in Connecticut, said July 1 that the investigation is continuing.

“There are no details that we can discuss at this time,” Thibault said.

Yale spokesman Tom Violante declined to comment on the case last week.

Two other people with connections to Yale have also been subjects of the investigation, though neither has been charged.

Officials investigated Norman Yarvin, also a Hamden resident and a former employee in the Yale computer science department, the Courant reported.

Yarvin told the Courant he returned from a trip to find authorities had taken guns, ammunition and books about explosives from his home. He said the items were objects of curiosity as opposed to the malicious intent to hurt someone.

In interviews with potential witnesses last month, law enforcement officials presented sketches of two men they were trying to identify and asked those interviewed if they knew of anyone who held a grudge against Yale. FBI officials searching for the person or persons responsible for the bombing have investigated at least three men associated with Yale.

Officers searching the Yale Law School after the bombing found firearms in one student’s room. Denis Delja LAW ’03, a member of the

Yale Law Gunners group, was questioned by FBI officials. Delja, who was not arrested or charged, graduated with his class.

Johnson was arrested when his parole officer found passages about explosives in his journal.

Johnson’s lawyer, Penn Rhodeen, said Johnson demonstrated “complete cooperation” with law enforcement officials.

“[Johnson] was placed in the detention for nearly a week as they have a right to do because he’s functionally an inmate,” Rhodeen said.

But Rhodeen said Johnson was released to his detention program in his parents’ home soon after he was re-arrested. “Corrections was certainly satisfied that it was appropriate to return him to the[home] program,” Rhodeen said. “We are pleased that he got fairly quickly back into his program and his routine.”

Johnson pleaded guilty in April 2002 to three counts each of first degree larceny and criminal mischief. As part of his plea deal, Johnson was required to repay Yale as fully as possible.

— The Associated Press contributed to this report.