Updated, 6:30 p.m. Former New Haven Police Chief James Lewis will be taking charge of the Yale Police Department in July.

Lewis’ appointment is a temporary one while Yale administrators conduct a national search for a permanent replacement. Lewis served as NHPD chief for 20 months and is widely seen as having revitalized the department and reduced city crime by more than 10 percent. He left at the end of February, saying he wanted to return home to Wisconsin to spend time with his children and grandkids.

But now he’s back.

“He’s here because of his stature, his experience and his willingness to pitch in and help while we search for a replacement,” said Deputy University Secretary Martha Highsmith, who oversees security matters.

Lewis’s return is already emerging as a source of tension between him and the department he left less than two months ago, with some expressions of dismay in the NHPD that Lewis left them only to come back in a Yale uniform.

Lewis’ appointment was announced in a memo from University Secretary Linda Lorimer to Yale security and police personnel Friday. Lorimer said in the memo that Lewis’s title will be Interim Director of Public Safety and that he will not be a candidate for the permanent position of police chief. Lewis will spend all of July in the city, learning the department, but then will spend only about two weeks every month at Yale, handing many day-to-day responsibilities off to YPD Assistant Chief Ronnell Higgins.

Current YPD Chief James A. Perrotti announced two weeks ago that he will be retiring at the end of the school year after 37 years as a Yale police officer, including 12 as YPD chief.

The chain of command for Yale police and security is also set to shift dramatically. Overall responsibility for police and security matters will be shifted from Lorimer’s responsibility in the Secretary’s Office into Human Resources and Administration, which Vice President Michael Peel oversees. Currently, Yale police and security officials report to Highsmith. Starting July 1, the officials will report to Associate vice President for Administration Janet Lindner, a former Chief Administrative Officer for the City of New Haven.

Highsmith said the shift of responsibility away from the Office of the Secretary is a part of an effort to balance the portfolios of all University officers. The Secretary’s Office will maintain control of emergency management and security for major events.

In an interview Friday, Highsmith said Lorimer had been in discussions with Lewis about taking the position at Yale even before he left the NHPD. In the later years of his career, Lewis became associated with coming into police departments to reorganize them and fix their problems. Highsmith says that is not the case now.

“There’s nothing here that needs fixing,” she said.

Lewis is the second former NHPD chief to take a high-ranking Yale security position. In January, former chief Francisco Ortiz took over as head of security guard operations, one of two parts of the Yale Security Department.

Highsmith said she is aware that Lewis’s appointment may give some the impression that New Haven officials are taking over all Yale security operations. But she said that is not the case: Lewis is only stepping in to help out during a transitional phase. She added that Lewis’s title of Interim Director was thought up expressly to counter feelings of NHPD overreach. Despite the special title, Lewis’s duties will functionally be the same as YPD chief, she said.

NHPD spokesman Joe Avery said the department only found out about Lewis’s appointment on Friday, the day it was announced. He would not comment further on the matter.

But police sources said the mood inside the NHPD toward Lewis’s return is one of disappointment and dismay. Lewis was widely popular while he was chief. Many officers wished he would remain in New Haven but understood Lewis when he said it was time for him to return home and spend time with his family.

In fact, at the December press conference announcing his departure, Lewis cited the plea of his daughter for him to return home as a principal reason for his stepping down.

But Police officers said his return to New Haven as a Yale employee has now made them question Lewis’s motivations.

“I’m very disheartened,” one officer said. “He wouldn’t stay for us, but he’ll come back for Yale? I don’t understand why he’s doing this.”

Reached by e-mail Friday, Lewis said Yale asked him just prior to his departure about helping the YPD transition to new leadership. He did not decide to return to New Haven until he was back in Wisconsin. Lewis said the interim job will be ideal for him.

“Yale was able to offer me a flexible position that will allow my wife and I to spend the majority of our time with our family in Wisconsin, while still allowing me to assist in an occupation that I enjoy,” he said.

As for leaving New Haven two months ago, he never really wanted to.

“If it had been possible to remain in a part-time position with New Haven, I would not have left,” he said.

But a part-time job would not have been practical, he added, because the NHPD needed a full-time chief to commit to a full, four-year term.

Highsmith said administrators are in the process of organizing a national search for a permanent new chief that is expected to hit full stride over the summer. She added that she thinks there will be many strong internal candidates. Current Assistant Chief Ronnell Higgins, who will be playing a leading role in helping Lewis manage the department, is expected to be among them.

“If he doesn’t apply, I will nominate him,” Highsmith said.

The last national search, in 1998, which led to the appointment of Perrotti as chief, took eight months. Highsmith said this current search could take a similar amount of time and that she expects Lewis to remain as interim director at least through the 2010 fall semester.

Lewis oversaw the NHPD during all of 2009, the year with the lowest city crime rate in the 20 years since police began keeping records.

Chicago police veteran Frank Limon was sworn in as NHPD Chief on Monday and has a contract with the city until at least 2014.