Chris Kyle: US Navy Seal sniper

Kyle pictured last year with his controversial bestselling book (AP)

Chris Kyle was an ex-US Navy Seal Sniper who, after four tours of Iraq, went on to write a bestselling book graphically chronicling his life as the US's most prolific marksman. Upon retirement he co-founded Craft International, a security company which provides training to military, police, corporate and civilian clients, and Fitco Cares, a foundation he helped establish for veterans with post-traumatic stress disorder (PTSD).

Kyle devoted much of his time to this cause and it was in this capacity, when helping another veteran, Eddie Ray Routh, at Rough Creek Lodge gun range in Texas that Kyle and his co-worker, Chad Littlefield, were shot by Routh. Routh fled the scene but was arrested several hours later near his home in Lancaster, Texas, more than 70 miles from the crime. It is believed that Routh, a former Marine, was suffering from PTSD and had a history of mental illness following his discharge.

Kyle rose to prominence in the services while serving four combat tours in Operation Iraqi Freedom and elsewhere between 1999 and 2009. During the battles in towns and cities such as Ramadi, Fallujah and Baghdad, he was part of an elite team charged with concealing themselves in and around the cities as troops cleared them of insurgents. Standing 6ft 2in tall and weighing a muscular 15 and a half stones, Kyle became a master at camouflaging and secreting himself seamlessly into the landscape and earned legendary status among his fellow SEALs, Marines, and US Army soldiers, whom he protected with deadly accuracy.

His first kill was in 2003. Kyle watched as crowds of Iraqis greeted a battalion of Marines entering a town when, through his scope, he noticed a woman cradling a toddler with one hand and holding a grenade in the other. He hesitated for a split second and pulled the trigger. "I had to do it to protect the Marines," he recalled. "You want to lose your own guys, or would you rather take one of them out?"

In a revealing interview Kyle admitted to being unsure and hesitant when confronted with killing someone for the first time. He said, "You think you can, but you never know until you actually are put in that position and you do it."

As his kill tally increased so did Kyle's reputation for deadly accuracy, prompting insurgents to put a $20,000 bounty on his head and to give him the nickname "al Shaitan" or "the Devil". He recorded a personal-record 2,100-yard kill while operating outside Baghdad. In 2009, Kyle left the Navy as a chief petty officer.

In 2012 he joined an ever-growing list of ex-combat troops, in particular from special ops forces, who have written memoirs about their wartime experiences. His book American Sniper: The Autobiography of the Most Lethal Sniper in US Military History, was criticised for drawing attention to his exploits by writing about the 160 insurgents he had killed. The Pentagon confirmed the 160 kills, though Kyle estimated the total was closer to 255. Regardless, Kyle holds the record for a US military sniper, set at 109 by a Marine sniper, Adelbert F Waldron III, during the Vietnam War.

Despite the criticism the book became a global bestseller with sales of over 800,000, and propelled Kyle on to the chat-show circuit. In one such interview he said he had not wanted to brag and put the number of kills in the book but the publisher insisted. Proceeds from the book were donated to the families of two fellow SEAL members who died in combat.

During an appearance to promote the book, Kyle appeared humble: "I had more kills, but that doesn't mean I'm better. I was just put into a position where I had more opportunities. I definitely cheated. I used a ballistic computer that tells me everything to do. So, I was just a monkey on a gun."

In the book Kyle explained that after his first kill, nothing further was required mentally. "I look through the 'scope, get my target in the cross hairs and kill my enemy before he kills one of my people." He illustrated how each kill was recorded in meticulous detail – the time and place, where the insurgent had stood and what they had been wearing.

Born in Odessa, Texas, in 1974, Christopher Scott Kyle was the son of a church deacon. Growing up on a ranch he enjoyed a number of outdoor pursuits including deer hunting and bronco riding in contests. He studied agriculture for two years at Tarleton State University, Texas, and then worked as a ranch hand, but was determined to join the Navy despite several pins in his arms following an accident. He gained admittance in 1999 and was quickly transferred to the SEALs, the US Navy's principal special operations force. He completed the punishing selection process, which mixes sleep deprivation and physical tests, and was selected to undergo sniper training.

After a decade in the military Kyle retired to spend more time with his family and joined other former SEALs to establish Craft International, a security company with the motto "Despite what your momma told you, violence does solve problems." He also helped found Fitco Cares, a foundation providing gyms and fitness equipment to keep soldiers active and providing counselling and medical networks. Fitco Cares director Trevor Cox described Kyle as a modest man who wanted to serve his country and help others, and who died "doing what filled his heart with passion – helping soldiers struggling with the fight to overcome PTSD."

Kyle became a reality TV personality on Stars Earn Stripes. He had recently spoken out against President Obama's proposals to tighten gun controls. He received numerous honours, including two Silver Stars and five Bronze Stars with valour; he also received the Grateful Nation Award, given by the Jewish Institute for National Security Affairs. Following his combat deployments, he became chief instructor for training Naval Special Warfare Sniper and Counter-Sniper teams, and later wrote the first Navy SEAL sniper manual.

At the time of his death, Kyle was being sued by Jesse Ventura, the former Minnesota governor and former professional wrestler, over claims in the book that Kyle punched him in a 2006 bar fight over unpatriotic remarks. Ventura claims the punch never happened.

Scott McEwan, who co-wrote American Sniper, said, "It just comes as a shock and it's staggering to think that after all Chris has been through, that this is how he meets his end, because there are so many ways he could have been killed in Iraq."

Christopher Scott Kyle, US Navy Seal: born Odessa, Texas 8 April 1974; married Taya (two children); died Glen Rose, Texas 2 February 2013.