At the Pierce County Sheriff’s Department, which polices a large part of the area near Joint Base Lewis-McChord, Rick Bulman, the department chaplain, has started programs to train SWAT team members and other officers on how to recognize a combat veteran who might have post-traumatic stress disorder.

He said that he doesn’t want police shooting troops but that he fears the risk of such deadly encounters is growing.

“We are having more and more issues with the military — suicides, domestic violence, DUIs, malicious mischief,” Bulman said. “They are trying to deal with issues unsuccessfully, and so they end up getting into trouble. But the situation can escalate if they are not treated properly.”

Lewis-McChord, an Army and Air Force installation south of Tacoma, is the largest military base on the West Coast, and thousands of service members from here have been deployed, often repeatedly, to Iraq and Afghanistan. The consequences of those tours are being felt both on distant battlefields and in the communities that surround the base, according to activists who work with veterans.

Confrontations with the police and criminal activity off the base are on the rise, and the legacy of battle is to blame, they say.

PTSD “is a chronic problem, and it’s been growing for 10 years,” said Stephen Kubiszewski, who co-founded PTSD Anonymous, which meets at a chapel at Lewis-McChord.

The 38-year-old soldier who is alleged to have killed 16 civilians over the weekend in southern Afghanistan was based at Lewis-McChord. Officials have said he had a traumatic brain injury in 2010 while in Iraq but was deemed fit for duty.

It remains unclear what prompted the shootings or whether anything in the suspect’s medical history could have led to his alleged actions. But the disclosure this week that he was from Lewis-McChord has refocused attention on trouble at the base, where a string of high-profile incidents had already raised questions about the scale of the mental health problems here and how the military is responding.

Last year, four members of a platoon from the base’s 5th Stryker Brigade, 2nd Infantry Division were convicted for their roles in a self-described “kill team” that murdered three unarmed Afghan civilians.

Two soldiers have been accused of waterboarding their children — one because the child couldn’t recite his ABCs and another because his foster son wet his bed. A 24-year-old Iraq war veteran fatally shot a ranger at Mount Rainier National Park. In April, David Stewart, 38, a decorated combat medic with two tours in Iraq, killed himself after leading police on a high-speed chase down Interstate 5 near Tumwater.

His wife, 38, who had been shot in the head, was found in the car beside him. Their 5-year-old son was found dead at their home.

And on Tuesday, a lieutenant colonel at the base was charged with felony harassment in connection with allegedly threatening to kill his wife, with whom he is going through a divorce, and his superior officer.

At least 12 suicides have been recorded in the past year among Lewis-McChord soldiers, and more than 60 since 2001, activists say.

“The problem of suicide is very severe,” said Rod Wittmier, program director of the National Alliance to End Veteran Suicide. “And we don’t understand the full dimensions of what is going on.”

The Madigan Army Medical Center at the base is under a wide-ranging investigation following allegations that a special psychiatric team altered staff clinicians’ diagnoses for hundreds of soldiers from PTSD to lesser conditions.

Fourteen soldiers who complained early this year that their PTSD diagnoses were unfairly changed were flown to Walter Reed National Military Medical Center in Washington for reevaluation. Last month, six of them had their PTSD diagnoses reinstated.

Soon after the reevaluations, Juliana Ellis-Billingsley, a leader of the forensic psychiatry unit that is accused, resigned.

“I find that I can no longer work in a system that requires me to sacrifice my professional and moral principles to political expediency,” Ellis-Billingsley wrote in her Feb. 23 resignation letter.

The Army’s preliminary review last month found that more than 280 additional soldiers evaluated at Madigan since 2007 had their diagnoses altered to less serious conditions, often adjustment disorders that receive fewer disability benefits.

Col. Dallas Homas, who heads the center, and William Keppler, a mental health chief at the hospital, were placed on administrative leave while the investigation continues.

The most dramatic evidence in the case, according to a congressional source who was briefed on it, is a PowerPoint presentation that Keppler offered to psychiatric and medical staff members. It emphasized that each soldier who receives a PTSD diagnosis costs the military $1.5 million over his or her lifetime in health benefits and pension payments.

Keppler referred calls about the case to military spokesmen, who referred questions to the Army surgeon general. Ellis-Billingsley did not respond to calls to her home seeking comment.

Nationwide, traumatic brain injuries among service members have been steadily rising each year since 2000, with 11,000 confirmed cases reported that year and 30,000 reported in 2011, according to the Defense and Veterans Brain Injury Center.

The Army surgeon general said that traumatic brain injury has been diagnosed in 135,000 soldiers from 2000 through 2011. But three-fourths of those injuries were classified as mild, and few troops suffer long-term symptoms.

“The overwhelming majority of military personnel who sustain a concussion/mild traumatic brain injury fully recover with proper rest and education with no residual symptoms,” surgeon general spokeswoman Maria Tolleson said in a statement. “Patients requiring ongoing treatment are not deployed to a combat zone or if in a combat zone, they are medically evacuated for further care.”

Tolleson said “a relatively small proportion of patients” suffer from symptoms that last more than six months after their concussion.

Ashley Hagemann, a Fort Lewis widow, said something is horribly wrong with the way the base handles traumatized soldiers who are shipped out for tour after tour without counseling for the deaths they have witnessed and the stress they have endured.

Hagemann’s husband had been with a unit stationed at Fort Lewis and committed suicide last year just before his eighth tour, which was to be to Libya, she said. Hagemann said her husband told her that God would never forgive him for what he had seen and done as a soldier.

Hagemann said she had a queasy feeling that the alleged gunman in the killings in Afghanistan’s Kandahar province was from her husband’s base.

“I already knew he had to be from Fort Lewis and had to have some sort of trauma,” she said. “I was angry knowing the military would deploy him, to not give him help he obviously needed.”

Leonnig reported from Washington. Staff researcher Julie Tate in Washington contributed to this report.