JACKSONVILLE, Fla. – A police officer who was battling cancer was found dead in his patrol car Friday morning from an apparent self-inflicted gun shot wound, according to the Jacksonville Sheriff's Office.

K9 Officer Ed Krawcyzk, 46, a 20-year veteran of the department, was on duty overnight and expected to get off at 4 a.m.

When he couldn't be reached overnight, dispatch alerted officers and he was found dead inside his patrol car around 2 a.m. just outside the Police Memorial Building on Bay Street.

Undersheriff Dwain Senterfitt said Krawcyzk had been battling cancer for five or six years.

"He has been undergoing cancer treatments," Senterfitt said. "He's come back and left, that kind of thing. At this point it's really early and we don't have much else."

Senterfitt said Krawcyzk was married with a family, and that he was also part of the JSO family.

"It hurts. It's a big family. I've known Ed most of my career and just like people in groups everywhere else, we all hurt when someone in our family is hurting," Senterfitt said. "We have people at his house with his family so well just work through this the rest of the day."

In January 2009, Krawczyk (pictured with his son) noticed a tumor on his neck that grew to the size of a grapefruit. It was a rare form of throat and mouth cancer. Krawczyk didn't use tobacco products and his doctors were puzzled.

"It's crazy, they said I had a better chance getting struck by lightning in Florida than getting this cancer," Krawczyk said.

His fellow officers held a spaghetti dinner benefit to help his family pay medical bills.

"It has been unbelievable, the amount of support we've had from our friends and family. If it was not for the love, prayers and support of these people we would not have been able to make it through," said Krawczyk's wife, Susan.

At that time Krawczyk was looking forward to returning to the force.

"He said, 'Hey, I'm going to beat this.' He said, 'Hey, I'm going to be back, I'm going to be back in this uniform and help protect the citizens of this city,'" said fellow officer Charlie Wilkie, Krawczyk's best friend.

Wilkie said Krawcyzk (pictured left with his son) was built like a soldier and had a real soft spot for his three children. He said that in four years, Krawcyzk beat cancer twice, all while doing the job he loved so much.

"Every time you saw him, you saw a positive person," said former JSO officer and Channel 4 crime analyst Ken Jefferson, a friend of Krawcyzk said.

That positivity is what Jefferson said immediately drew him to Krawcyzk, and a trait that drew hundreds to his side after his cancer diagnosis.

"In my opinion, he took the diagnosis very well," Jefferson said. "And what I mean by that is, he didn't like it, but he was determined to fight it, determined to beat it, his attitude was always positive."

Wilkie said Krawcyzk underwent months of treatment for nasopharyngeal carcinoma, a rare and often times aggressive throat and mouth cancer.

In August 2010, he had a setback, with a cancerous tumor removed from his femur and hip socket.

By 2011, Krawcyzk had lost nearly 30 pounds but was cancer free and back to work with a renewed hope and spirit.

"He was somewhat different in the fact that he had a different perspective on life," Jefferson said. "He appreciated people more, he appreciated life more. He talked about his family a lot."

Close friends say the devoted father had seemed more tired and preoccupied in his final days, but because of his strong front and no-nonsene attitude, they didn't push for an explanation.

Now with a wife, two sons, a daughter and a mountain of loved ones and colleagues left behind, all can only wonder what could have driven a man who fought so hard for his life to suddenly decide to take it.

Doctor: Cancer can take physical, emotional toll

Doctors say head and neck cancers are very different than cancers in other parts of the body because the effects can be so obvious. While they are quick to point out treatment is different for every patient, they say it typically lasts between six and eight weeks.

"Suicide is very rare among cancer patients, so we're always sad to hear when tragic events like this occur," said Dr. Jessica Bahari-Kashani, of Memorial Hospital.

Bahari-Kashani never treated Krawcyzk but said the physical and emotional toll cancer can take on a patient can be overwhelming.

"It's very tough emotionally, physically and financially," she said. "All aspects of your life can be affected."

Bahari-Kashani said Krawcyzk's rare form of cancer, along with chemo therapy and radiation treatment, can present side effects including weight loss, lack of energy, difficulty swallowing and depression.

"During the course of the treatments, they're monitored very closely by their doctors and are encouraged to got to support groups," she said. "And we check for any signs of depression and we try to screen people very well."

Funeral arrangements are still pending, for Krawcyzk, but friends say it could be as early as next Tuesday.