Smiling as he meets his family at the airport after arriving from Ankara, Turkey, this is the mastermind of the Boston Marathon bombing as he arrives in America - where he was welcomed as a refugee.

Tamerlan Tsarnaev, the second from the left in the photo below, stands taller than his father Anzor, despite being just 16 years old in the picture taken in 2003.

To his right is his younger brother Dzhokhar, nine, who Tamerlan would later radicalize and turn against America, a country which gave them both free housing, an education and a future.

Their sisters Ailina and Bella are also in the photo which was obtained exclusively by DailyMail.com from investigative journalist and author Michele McPhee.

Tamerlan Tsarnaev, second from the left, stands taller than his father Anzor despite being just 16 years old in 2003. At left in the photo is his younger brother Dzhokhar, nine, who Tamerlan would later radicalize. Their sisters Ailina and Bella are also pictured

Tamerlan Tsarnaev (left and right) was a federal informant who turned on America after his citizenship application was rejected, according to new bombshell book by Michele McPhee

In her book Maximum Harm: The Tsarnaev Nrother, the FBI and the Road to the Marathon Bombing to be published in April, she tells how U.S. authorities believed Anzor Tsarnaev's claimed his life was in danger due to his Chechen heritage and his family was granted political asylum.

McPhee's theory - which she admits she cannot definitively prove - is that Tamerlan was a federal informant and that he turned on America after his citizenship application was rejected.

McPhee writes that Tamerlan expected to be granted citizenship quickly and his anger grew when the process was delayed.

He was initially told to come in for his swearing in ceremony in October 2012 but it was put off.

The U.S. Immigration service wrote to Cedarleaf, the FBI terrorism chief in Boston, and asked if he was a 'national security concern'. Cedarleaf replied that there was 'nothing I know of'.

In January 2013 Tamerlan tried again to get his citizenship and had another interview where he was asked about his arrest related to a domestic violence charge.

McPhee says that Tamerlan 'fully expected to walk way' with his citizenship'. Instead. his status was delayed again due to paperwork issues.

Two weeks later, on February 6 2013, an 'angry Tamerlan walked into Phantom Fireworks in Seabrook, New Hampshire, and asked for the "biggest and loudest" pyrotechnics in the story', McPhee writes.

McPhee, an Emmy-award nominated reporter with the ABC News investigative team, writes that he felt 'double crossed' and that he turned on America for failing to keep up its side of the bargain after he worked for them.

In Maximum Harm, McPhee says that as a result the federal government played a 'direct role in creating the monster that Tamerlan Tsarnaev became'.

She argues that they recruited Tamerlan as an operative in late 2010 and that he was the 'perfect candidate' because he was 'broke, desperate for citizenship and with a new wife and a baby to take care of, he spoke fluent English, Russian and a dialect of Chechen'.

Tamerlan was not jailed for his involvement in a triple murder in 2011 because he was 'too valuable as an asset working for the federal government on a drug case with ties to overseas terrorism'.

In 2001 Tamerlan's father Anzor (above with Tamerlan) moved to the U.S. In 2003 the younger Tsarnaev sisters arrived, followed by Tamerlan who had dreams of becoming a professional boxer and won two titles as the Golden Gloves heavyweight champion of New England in 2010

Tamerlan was also providing them with intelligence on the mosque he attended and its ties to Al Qaeda.

Another issue was where Tamerlan got his money from.

On Tamerlan's death certificate the Medical Examiner listed 'Never Worked' as his occupation but he drove a Mercedes.

McPhee writes: 'History has shown that working for the federal government as an informant can be lucrative.

'Tamerlan got away with much villainy that only a hands-off policy formulated at local level by one or more agencies responsible for national intelligence could have engineered'.

McPhee told DailyMail.com that she believed that the CIA were running Tamerlan while he was in Russia and that the FBI were in charge of him when he returned to America, citing sources she had spoken to.

If the case McPhee makes for Tamerlan's working for the government proves untrue, then a catalog of national security failings allowed Tamerlan to travel to Russia where he was further radicalized and return to the U.S. even though he was on two terror watch lists.

She says that none of the lessons from the 9/11 Commission about intelligence sharing were learned and were a major factor in allowing the Boston Marathon bombing to happen.

McPhee told DailyMail.com that unless law enforcement and intelligence agencies do not fix the same problems that led to the 2001 World Trade Center attacks it is just a matter of time before there will be another atrocity on U.S. soil.

The Boston Marathon bombing was the worst terrorist attack in America since 9/11, leaving three dead and wounding several hundred others, many who lost limbs.

Tamerlan, 26, died during a shootout on the streets of Boston after killing Massachusetts Institute of Technology police officer Sean Collier.

Dzhokhar, now 23, was captured alive and put on trial. After convicting him, a Boston jury sentenced him to death.

Immigration documents from when Tsarnaev first moved to the U.S. show a totally different person from the image of Tamerlan in a head dress or at the scene of the bombings. It is unclear as to why his application was processed in Turkey

McPhee took three years to research and it traces the Tsarnaev family history back to Dagestan, where they moved from their native Kyrgyzstan.

In 2001 Tamerlan's father Anzor and his mother Zubeidat moved to the U.S. along with Dzhokhar on 90-day tourist visas.

In 2002 they filed for political asylum saying they were under threat of death because of Anzor's Chechnyan heritage and their application was successful.

The following year the younger Tsarnaev sisters arrived, followed by Tamerlan. The photo of him at the airport shows a tall, strong 16-year-old who, like his father, was a boxer.

The U.S. government had, unwittingly, just admitted a man who would go on to become one of its most notorious terrorists.

Life in the U.S. however was not straightforward for the Tsarnaev family and by 2006 not a single member of the family had held a job, including Anzor.

Their rent was paid for with a federal subsidy, their food was paid for by the SNAP benefits program and their clothing was paid for using cash from EBT cards, another government welfare program.

The only work they did do was not declared, McPhee writes, such as Zubeidat doing facials in her apartment for cash. Tamerlan delivered pizzas while Dzhokhar sold drugs, according to court documents.

Tamerlan had dreams of becoming a professional fighter and won two consecutive titles as the Golden Gloves heavyweight champion of New England in 2010.

The Boston Marathon bombing was the worst terrorist attack in America since 9/11, leaving three dead and wounding several hundred others

But that year he was barred from fighting in the National Tournament of Champions because he was not a citizen, essentially ending his career.

This was the point where his life began to go off the rails and he became increasingly radicalized.

The following year Tamerlan is said to have directly taken part in the brutal murder of three people who had their throats slashed in Waltham, Massachusetts.

The victims, one of whom was Tamerlan's best friend, had their heads pulled back and their throats slit from ear to ear, investigators said.

McPhee writes that on March 4 2011 the Russian intelligence service, the FSB, took the highly unusual step of warning the FBI legal attaché in Moscow about Tamerlan and his mother - that they were becoming 'adherers of radical Islam'.

The letter, which contained extensive detail about the family, said that Tamerlan had 'changed drastically since 2010' and was preparing to travel to Russia to 'join unspecified groups'.

The information was handed to David Cedarleaf, the special agent in charge of the FBI's Boston field office, who carried out a 'threat assessment' of Tamerlan and interviewed his parents.

However he did not speak to Tamerlan's wife Katherine Russell, a Muslim convert, nor did he visit the controversial mosque in Cambridge where Tamerlan prayed even though it was connected to radical Islamic terrorism and its founder would later be jailed for 23 years for giving money to Al Qaeda.

Three months later Cedarleaf closed his investigation and sent a message to the FSB on August 28 2011 through the bureau's legal attaché in Russia saying there was 'nothing derogatory' about the Tsarnaevs.

Tamerlan's brother, Dzhokhar, now 23, was captured alive and put on trial and after convicting him, a Boston jury sentenced him to death

Inexplicably Tamerlan was nevertheless put on two terrorist watch lists.

And in a further bizarre twist, in January 2012 he traveled to Russia 'without a hitch' despite being on the lists and not having a valid passport, instead using his residency documents and a passport issued in Kyrgyzstan that was due to expire months later.

According to McPhee: 'All of this was suspicious. No one would dismiss such detailed information about a man that seemed to be exactly the sort of dangerous person that FBI director James Comey warned about, who posed the greatest threat to the US homeland; an American jihadi.

'Law enforcement officials in Massachusetts began to say that Tamerlan was an informant for the feds, a spy sent to Russia to help track and kill the men he was in contact with. They believed he was working for the government, motivated by the promise of citizenship'.

When he arrived in the Dagestan region of Russia, Tamerlan met with Magomed Kartashov, Zubeidat's second cousin, a former Dagestan cop who had become an Islamist leader and had declared war against Russia.

He appears to have been radicalized further at the fundamentalist Salafi mosque in Makhachkala, the region's capital.

Michele McPhee (left) took three years to research Maximum Harm: the Tsarnaev brothers, the FBI and the Boston Marathon bombing, which will be released in April

According to McPhee, Tamerlan could have provided intelligence that led to Russian intelligence services carrying out a raid in Utamysh, a small village in the Kayakent District of Dagestan.

Among the dead was William Plotnikov, one of his friends.

The following day, Tamerlan, or somebody acting for him, paid for him to fly back to America.

McPhee says that on Tamerlan's return to the U.S., Tamerlan was not even stopped for an additional security screening at New York's JFK airport, even though it should have been mandatory given he had been away for longer than six months.

Being on the terrorism watch list meant that it should have triggered an alert every time he traveled, but when he landed at Boston's Logan Airport on July 12 2012 there were no issues at all and a customs agent scanned his green card into the system and let him in.

McPhee says that this was the 'very loophole in immigration laws that the 9/11 Commission had said needed to be closed'.

More worryingly, the customs agent, Jim Bailey, later said he 'cannot recall' if he told the FBI that Tamerlan came into the U.S. without a passport.

Bailey later said that customs and border agents communicate with the FBI about possible terrorist suspects sometimes using just a 'sticky note'.

McPhee writes: 'Surely to stop Tamerlan at the airport for additional screening based on his physical profile alone - he was a dark-skinned Muslim male with a long beard - or because he was leaving a terrorist hotbed would have been insensitive racial profiling.

'But the idea that a man whose name was on two terrorist watch lists somehow managed to clear customs because government officials claimed his name was misspelled on those lists is inconceivable.

'This is especially true given the multi-million dollar computer program the Department of Homeland Security had purchased to prevent that very sort of thing from occurring'.

McPhee says that ultimately she wants her book to be a tribute to the work of the law enforcement officers who caught the Tsarnaev brothers.

She said: 'In the end it was amazing police work that tracked these guys down and I want to pay tribute to that'.