His name appears above radical internet postings praising Islamic suicide bombers — something that the FBI was alerted to six months ago.

He had frequent arguments with soldiers at Fort Hood because of his declarations that fellow Muslims “should stand up and fight against the aggressor”, and his vocal opposition to US troops in Iraq and Afghanistan.

He even appeared to celebrate the shooting dead of a soldier at an army recruiting centre in Arkansas in June, carried out by a Muslim convert. He said at the time that Muslims should strap on suicide bombs and detonate them in Times Square.

These were the extraordinarily provocative statements and actions of the army psychiatrist Major Nidal Malik Hasan in the months before his deadly shootings at Fort Hood — a massacre that began with him shouting “God is Great” in Arabic.

The apparently clear signs of Hasan’s growing anti-Americanism prompted questions and anger yesterday over why he was never investigated — an action that could have prevented the tragedy at the Texas Army base on Thursday.

Hasan, 39, an American-born Muslim who grew up in the Washington suburbs and joined the Army out of patriotic duty, had also told relatives that he had been harassed because of his religion after the September 11 attacks, and called derogatory names such as “camel jockey”.

“Some people can take it and some cannot,” his aunt, Noel Hasan, said. “He had listened to all of that and he wanted out of the military.” Hasan spent months trying to leave the Army, including hiring a lawyer. He offered to pay back the money the Army spent sending him to university and medical school, but to no avail.

His cousin, Nader Hasan, said he had recently expressed deep concern about being posted to Afghanistan or Iraq — he was due to go to Iraq at the end of this month. He did not want to go because of his recent experiences. For the past six years, as a psychiatrist, he had counselled soldiers returning with post-traumatic stress disorder.

“He was mortified by the idea of having to deploy,” Nader Hasan said. “He had people telling him the horrors they saw over there. He was doing everything he could to avoid that.

“He wanted to do whatever he could within the rules to make sure he wouldn’t go over.” Going to Iraq or Afghanistan had become his cousin’s “worst nightmare”.

Yet it also appeared likely yesterday that his fear of being deployed was probably because of a revulsion of being part of an operation in which Muslims would be killed. Hasan’s faith had intensified in recent years, first after the deaths of his parents in 1998 and 2001, and then with his mounting opposition to the wars in Iraq and Afghanistan. Colonel Terry Lee, who worked with Hasan in Fort Hood’s psychiatric unit, said that his colleague had begun making “outlandish” comments about the American presence in Iraq and Afghanistan.

“He said, precisely, that maybe the Muslims should stand up and fight against the aggressor,” Colonel Lee said, adding that after Barack Obama was elected, Hasan expressed hope that the new President would end both wars. When that did not happen, Colonel Lee said, Hasan, who he described as a loner, “became more agitated about the conflicts”. He got into frequent arguments with soldiers because of his opposition.

After the shooting in Little Rock, Colonel Lee added: “He seemed happy about it. He said ... maybe we should get out [of Iraq and Afghanistan]. He said maybe we should have more of these — people should strap bombs on themselves and go into Times Square.” Six months ago, the FBI was alerted to a posting on a website, Scribd.com, under the username “NadalHasan”, comparing the actions of an American soldier who threw himself on a grenade in Iraq with those of Islamist suicide bombers.

“[The soldier] intentionally took his life for a noble cause, saving the lives of his soldiers. To say that this soldier committed suicide is inappropriate. It’s more appropriate to say he is a brave hero that sacrificed his life for a more noble cause,” Nadal Hasan wrote. “Scholars have paralleled this to suicide bombers whose intention, by sacrificing their lives, is to help save Muslims, by killing enemy soldiers. If one suicide bomber can kill 100 enemy soldiers because they were caught off guard, that would be considered a strategic victory.”

US officials said the FBI looked into the posting but had not begun an official investigation by the time of the shooting.

Faizul Khan, a former imam at a mosque where Hasan worshipped in the Washington suburb of Silver Spring, said he often talked about his desire to find a wife. Hasan had filled out a form at the mosque for those seeking wives. Mr Khan said Hasan was devout, and would pray every day, often in military uniform. “I got the impression he was a committed soldier,” Mr Khan said. “We hardly ever discussed politics. Mostly we discussed religious matters, nothing too controversial, nothing extremist.”

Hasan’s story is also one of a person who grew up determined to embrace the American life, only to end up poisoned against the country. He was born in north Virginia, to parents who immigrated from the West Bank town of el-Bireh, near Jerusalem. His parents owned restaurants and a shop. Hasan had two brothers, one returned to Jerusalem and married. The other lives in Virginia. The family prospered in the US, with relatives in banking, medicine and law.

Hasan joined the Army against his parents’ will: “His parents didn’t want him to go into the military,” Mr Hasan said. “He said, ‘No, I was born and raised here, I’m going to do my duty to the country’.”

Hasan gained an undergraduate degree in biochemistry and his medical degree in Maryland, just outside Washington. He then moved to the Walter Reed Medical Centre in Washington, the country’s leading rehabilitation centre for wounded soldiers returning from war, where he pursued psychiatry, first as an intern then as a resident and, last year, a Fellow. After six years, he was posted to Fort Hood this summer. Colonel Lee said he wanted to know why Hasan had been transferred out of Walter Reed. “Something must have happened,” Colonel Lee said.

The neighbour said that at 5am on the morning of the shootings Hasan had left a phone message thanking him for being such a good friend. Later in the morning, he gave another neighbour a copy of his Koran.

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