A retired Yale employee who was arrested Thursday after bringing an unloaded shotgun and ammunition to a University building will never again return to campus, his father said Monday.

“They don’t have to be afraid of him,” Frank Petrini Sr., of Orange, Conn., said of his son, former Physical Plant worker John Petrini. “He’s never going to go anywhere near there. I guarantee it.”

Five days have passed since police arrested Petrini, 61, at a parking lot outside the University’s human resources office at 221 Whitney Ave., and Petrini was neither seen nor heard from by employees there on Monday. Petrini was released from custody Friday after he made an agreement with the University that he would both appear at his court date and stay off campus property.

Petrini was neither seen nor heard from Monday, as workers said they tried to work normally — albeit cautiously.

“People are trying to go on as business as usual with a more heightened sense of awareness,” said Shirley Conyers, a publishing assistant for Yale’s Publishing Services Center. “That’s what we should have been doing all along.”

Yale Police Chief James Perrotti said Saturday that the department had a plan in place to deal with Petrini, although he did not then provide specific details of the plan. Perrotti could not be reached for comment Monday, although a security guard stood in front of 221 Whitney Ave. throughout the day. At 155 Whitney Ave., the front door — unlocked last week — required keycard access.

Petrini may have been targeting human resources staff in the building, University Vice President and Secretary Linda Lorimer said after Petrini’s arrest. Last year, Petrini was denied an appeal he made after the University refused to pay him retirement benefits.

Petrini walked into 155 Whitney Ave. on Thursday and asked an employee for the Human Resources Department. After directing Petrini to that department’s new location — human resources staff members moved to 221 Whitney Ave. over the summer — the employee called the Yale Police Department to report Petrini’s suspicious behavior. One minute later, after Petrini got out of his car at a parking lot near the new building, police arrested him.

Petrini was detained after his arrest but was released the following day from New Haven Superior Court on the promise that he would return for an arraignment scheduled for Oct. 1.

Petrini’s release surprised a half-dozen workers interviewed by the News on Monday.

“I don’t think I feel less safe or more safe,” Conyers said. “I live in New Haven, and it’s a big city. I try to be cautious of my surroundings.”

But one Yale employee at 155 Whitney Ave. said she and her colleagues are still shaken up by Petrini’s entering the premises. The closed front door provides some relief, she said, but “it’s too bad that had to happen” before precautions were taken.

Petrini was released because with no criminal record he was not considered a threat, his lawyer, Jamie E. Alosi, said over the weekend. His shotgun was also seized, she added. Alosi could not be reached for comment Monday.

Isaac Arnsdorf and Harrison Korn contributed reporting.