MADISON, Wis. — For soldiers patrolling in Iraq and Afghanistan, death can come from a bomb hidden in a trash pile or an innocent-looking face in the crowd. Returning home alive can depend on the quick turn of a steering wheel or pull of a trigger.

Those heightened survival instincts don't always translate when those soldiers return home to their jobs as law enforcement officers.

In interviews with The Associated Press and in dozens of anecdotes compiled in a survey by the International Association of Chiefs of Police and the U.S. Bureau of Justice Assistance, officers described feeling compelled to use tactics they employed in war zones after they returned to work in the U.S. and feeling less patient toward the public they serve.

One officer said he felt compelled to fire his gun in the air to disperse an unruly crowd in California.

Others said they felt wary about being flanked when working crowd control. And others said after seeing the hardships ordinary Afghans and Iraqis lived with, it's hard to care about complaints over pet droppings.

The report, which was issued late last year, warns that the blurring of the line between combat and confrontations with criminal suspects at home may result in "inappropriate decisions and actions — particularly in the use of ... force. This similarity ... could result in injury or death to an innocent civilian."

In two high-profile cases, officers blamed their overzealous use of force on complications from their military service.

Wayne Williamson, an Austin, Texas, police officer who served 18 months in Iraq, was fired in 2008 after he opened fire on a fleeing assault suspect in a crowded parking lot. A dispatcher had reported that the suspect was carrying a knife, but Williamson said he didn't see a weapon when he fired.

None of the rounds hit their mark, but one struck a minivan with two children inside. They were not injured.

Williamson told investigators he had been having trouble readjusting to some aspects of civilian life and that he had trouble differentiating between Iraq and Austin during the confrontation.

"In Iraq, if a bad guy gets away, he could come back and blow you up or blow up someone who works with you," Williamson told the AP. "You do everything you can to make sure the bad guy doesn't get away. ... I can't absolve myself of Iraq. How deeply it affected me, I don't know ... I'm not the same person who left."

His police chief didn't buy it, noting in the disciplinary records that Williamson hadn't previously showed signs of distress.

On March 5, a former sheriff's sergeant who served in the Gulf War before leaving the Army 17 years ago was sentenced to 18 months in prison for repeatedly punching a handcuffed suspect in the face in the back of his squad car. Scott Krause, 38, has post-traumatic stress disorder and doesn't remember the incident, which was videotaped, Krause's psychotherapist told the judge at the sentencing hearing.

Krause's former boss, Milwaukee County Sheriff David Clarke, said Krause never told his colleagues he was struggling.

The survey was based on interviews with 53 law enforcement officers who had returned from serving in the National Guard or reserves, as well as written responses from 340 returned veterans and 112 police chiefs.

STAKES LOWERED

Laura Zimmerman, a psychologist who contributed to the study, said the irritability some respondents reported feeling with citizens back home stems from a sense that the stakes have been lowered. Officers have gone from helping build nations to writing speeding tickets, she said.

"They've seen bigger problems now. Coming back to policing, the mission doesn't feel as critical," she said. "Once you raise the bar, coming back down is just difficult. I think it's just that feeling of non-purpose here."

Todd Nehls, the sheriff of Dodge County, Wis., and a colonel in the Wisconsin National Guard, said that after spending a year stationed in Afghanistan, he's had less patience for small complaints back home. After seeing people go without electricity and walk miles for fresh water, he said, you quickly grow tired of citizens complaining about dogs urinating in their neighbor's lawn.

Zimmerman said the urban nature of the Iraq war, as compared to the jungle warfare that dominated the Vietnam War, may have made it more difficult for some returning officers to adjust to urban life back home. She said examples like Williamson's shooting are rare, but that potential is there.

"Now it is easier to muddle the environments," Zimmerman said.

HELP REINTEGRATE

The study's authors hope it will help law enforcement agencies develop protocols to help reintegrate the thousands of officers called up since the start of the war in Afghanistan.

The U.S. Department of Veterans Affairs offers no programs specifically for police officers, but many larger law enforcement agencies have started reintegration programs that include visits with psychologists, weapons refresher training and rides with trainers.

The Los Angeles County Sheriff's Department, which lost 364 of its employees to deployment shortly after the Sept. 11, 2001, terrorist attacks, began requiring returning deputies to go through weapons and driving refresher training and ride-alongs before returning to patrol.

TROUBLE SLEEPING

Jung Kim, a psychologist who interviews every returning deputy as part of the department's reintegration program, said many report having trouble sleeping, feeling safe on patrol in their squad cars.

"(Overseas) they go over medians and bump cars in front of them to get them out of the way," Kim said. "Obviously you can't do that."

Clarke, the Milwaukee County sheriff, said the squad car beating has led him to look into how other agencies deal with returning veterans. He said it's important that returning officers find the strength to talk openly about their problems.

"If the person doesn't develop that courage to say, 'hey, I need help,' it's very difficult to help them before they reach a breaking point," Clarke said.