The Oakland Police Department, reeling from budget cuts, is planning an organizational overhaul that will push more officers onto the streets, but could undermine its ability to investigate murders and other serious offenses at a time when the homicide rate is soaring.

The changes involve disbanding the Criminal Investigation Division and consolidating the division’s individual units, including homicide and assault, into a new major crimes unit in which officers will be responsible for investigating a variety of offenses.

It was unclear how many of the division’s 40-to-45 officers would be assigned to that unit; the rest would be put on patrol, officials said. The O.P.D. currently has just nine homicide investigators.

The restructuring, to be phased in over the next few months, represents the latest hard choice for a department that has lost more than 150 officers to layoffs and attrition the past two years. Officials said the move was necessary to ensure that the O.P.D. continues to have enough officers to respond to 911 calls.

But they acknowledged there is a tradeoff: the restructuring is likely to limit the department’s ability to investigate some major crimes. The city had 35 murders in the first 18 weeks of 2011.

“As we look to provide better customer service on the front end, some of our other priorities will have to drop off, just by sheer volume and demands for service,” Assistant Police Chief Howard A. Jordan said in an interview.

Dom Arotzarena, president of the Oakland Police Officer’s Association, said department officials briefed the union on the move for the first time last week.

“They are going to totally change investigations,” said Arotzarena, a former homicide detective. “And I don’t necessarily think it’s going to be good. They are virtually giving up on investigations for burglary and any kind of theft.”

Referring to the investigative television drama Law & Order, Arotzarena added: “Law & Order doesn’t apply to the Oakland P.D. anymore. And it’s not like we’re Fremont; we’re Oakland. People are getting killed here.”

Jordan said the O.P.D. remained committed to investigations and the reorganization will provide additional support. Under the new system, he said, four-officer teams headed by a sergeant will investigate major crimes.

Jordan said the O.P.D. modeled the changes after restructuring in cities like Sacramento and San Diego, where police departments have also been hard hit by budget crises. The violent-crime rate for Oakland (pop. 391,000) is nearly double that of Sacramento (pop. 466,500) and more than three times that of San Diego (pop. 1.3 million), according to a 2010 comparative survey conducted by the O.P.D.

Oakland had the fifth-highest crime rate in the nation last year, according to CQ Press, an independent publisher that compiles an annual list of crime statistics for metropolitan areas. 

Shootings are so common -- there were 16 over a seven-day period this month -- the department no longer issues a news release unless a homicide occurs.

Jon M. Shane, a former police captain who is now an associate professor at John Jay College of Criminal Justice, said other police departments are going through similar restructurings.

Such efforts can ultimately make the departments more efficient, Shane said. “I believe this is forcing police departments to be a whole lot smarter in the way they approach crime,” he said. “They can’t just throw cops at the problem.”

But he said the measures often create more work, as investigators are forced take on a multiplicity of crimes.“I don’t envy the police officers that are facing these problems,” Shane said. “Nor the chiefs, by the way.”