After being suspended Friday for alleged misconduct, New Haven Assistant Police Chief Peter Reichard resigned Monday, ending the department’s investigation of his behavior.

Reichard was relieved of duty after a number of civilians and his fellow police officers filed several complaints about his conduct. He is the second assistant chief to leave the department this week, and by the end of the month only one of the NHPD”s top officials, Assistant Chief Stephanie Redding, will remain.

Redding will be appointed acting chief of the NHPD after the current chief, James Lewis, leaves at the end of the month, Mayor John DeStefano Jr. said Monday.

Reichard surrendered his gun and badge and was escorted out of police headquarters Friday after a heated confrontation with Lewis, and Lewis said there would be an internal investigation into the complaints against him. But when Reichard retired Monday, Lewis said the investigation will not proceed.

Reichard could not be reached for comment Tuesday.

The most serious charge against Reichard is that he threatened a detective in September after he wore a white suit and white shoes to work. After the detective filed a complaint and New Haven Register reporter William Kaempffer wrote about the incident, Reichard sent Kaempffer an e-mail threatening to arrest him.

Ward 23 Alderman Yusuf Shah said just because someone retires does not mean investigations into wrongdoing should be terminated but would not comment directly on the investigation into Reichard.

Yale Police Chief James A. Perrotti said he has known Reichard for most of Reichard’s 22-year career and is saddened by how it has ended.

“It’s just terrible for someone to go out this way,” he said. He added that, though he would need to know all the details first, he probably would have acted as the NHPD did and stopped the investigation had Reichard been in his department.

Until Friday, Reichard had a clean record and was a candidate to become the next police chief . When Lewis announced his departure in December, Reichard said he would be honored to serve as chief if the mayor offered him the job. Lewis, who suspended Reichard, had promoted him to assistant chief in September 2008.

Shah, a member of the Board of Aldermen’s public safety committee, said he thought Reichard could have become the city’s police chief and is “saddened to hear there was so much of a problem with his style of management and leadership.”

Shah added that he has “mixed feelings” about whether the position should be given to someone within the ranks at the New Haven Police Department. Even though he thinks Redding would be great in the position, he said an outsider might be the best choice for the department.

When Redding takes on the role of acting chief next month, she will not have any assistant chiefs to aid her. Richard Epstein, chairman of the Board of Police Commissioners, said that he does not know who will be the new assistant police chiefs or when they will be appointed.

But Redding has experience as acting chief. In 2008, she was acting chief for several months after former Chief Francisco Ortiz left and before Lewis arrived. Perrotti has known Redding for a long time and said no one should be worried about whether she can handle the job.

“She’s terrific,” he said. “She’ll take them where they need to go.”

Lewis became Chief in July of 2008 and brought two of the outgoing assistant chiefs with him from California.