LONDON (AP) – They had diverse backgrounds, coming from countries around the globe, but all shared youth and worked in medicine. They also had a common goal, authorities suspect: to bring havoc and death to the heart of Britain.

The eight people held Tuesday in the failed car bombing plot include one doctor from Iraq and two from India. There is a physician from Lebanon and a Jordanian doctor and his medical assistant wife. Another doctor and a medical student are thought to be from the Middle East.

All employees of the United Kingdom’s National Health Service, some worked together as colleagues at hospitals in England and Scotland, and experts and officials say the evidence points to the plot being hatched after they met in Britain, rather than overseas.

“To think that these guys were a sleeper cell and somehow were able to plan this operation from the different places they were, and then orchestrate being hired by the NHS so they could get to the UK, then get jobs in the same area – I think that’s a planning impossibility,” said Bob Ayres, a former U.S. intelligence officer now at London’s Chatham House think tank.

“A much more likely scenario is they were here together, they discovered that they shared some common ideology, and then they decided to act on this while here in the UK,” he said.

No one has been charged in the plot in which two car bombs failed to explode in central London early Friday and two men rammed a Jeep Cherokee loaded with gas cylinders into the entrance of Glasgow International Airport and set it on fire the following day.

Investigators believe the main plotters have been rounded up, including one in custody in Australia, though others involved on the periphery, including at least one British-born suspect, were still being hunted, a British government security official said, speaking on condition of anonymity because of the sensitivity of the details.

British-born Muslims behind the bloody 2005 London transit bombings and others in thwarted plots here have been linked to terror training camps and foreign radicals in Pakistan, and the official said Pakistan, India and several other nations were asked to check possible links with the suspects in the latest attacks.

The educational achievements of the suspects in the car bomb attempts is in sharp contrast to the men that carried out the deadly July 7 transit bombings two years ago. The ringleader of that attack, Mohammed Siddique Khan, had a degree in business studies, but with low marks, and his three fellow suicide bombers had little or no higher education.

In the current case, Muhammad Haneef, a 27-year-old doctor from India arrested late Monday in Brisbane, Australia, worked in 2005 at Halton Hospital near Liverpool in northern England, hospital spokesman Mark Shone said.

Another Indian doctor, 26, arrested late Saturday in Liverpool, worked at the same hospital, Shone confirmed, but refused to divulge his name.

A third suspect, Mohammed Jamil Asha, a 26-year-old doctor from Jordan of Palestinian heritage, was arrested Saturday with his wife, Marwa Asha, 27, who was identified in British media reports as a medical assistant. He worked at North Staffordshire Hospital, near the Midlands town of Newcastle-under-Lyme.

A doctor at Royal Alexandra Hospital in Glasgow, who refused to give his name, said he recognized Asha as a doctor who kept an office there – the same hospital where another suspect, Bilal Talal Abdul Samad Abdulla, worked.

According to friends of Abdulla’s family in Iraq, the 27-year-old doctor came to Britain after graduating from medical school in Baghdad. He was a passenger in the Jeep Cherokee that rammed into the Glasgow airport.

The Jeep’s driver – identified by staff at Royal Alexandra Hospital as a Lebanese doctor named Khalid Ahmed – was in critical condition at that hospital from burns suffered in the attack. Police would not confirm his identity.

Investigators believe the same men who parked the explosives-laden cars in London may have also driven the blazing SUV in Glasgow, the British security official said.

The final two suspects, ages 25 and 28, were arrested by police Sunday at Royal Alexandra Hospital. Staff said one was a medical student and the other a junior doctor, without giving their names. British media said they were from Saudi Arabia, but police refused to comment.

Dr. Shiv Panbe, former chairman of the British International Doctors Association, said the two Indian nationals in custody were Muslims.

“It is very upsetting news,” Panbe said of their alleged involvement. “It is an abuse of trust and respect – everyone should be able to love their doctor.”

Azmi Mahafzah, a teacher at the University of Jordan’s medical school, said he knew the suspect Asha during his studies and training there in 1998-2004. He said he didn’t think Asha was religious. “He is not a fanatic type of person,” Mahafzah said.

Asha’s family also denied he was a militant or had links to terrorism, as did the family of Asha’s wife, Marwa.

“Marwa is a very educated person and she read many British novels to know England better, a country she liked so much,” her father, Yunis Da’na, told The Associated Press in Jordan.

British authorities have refused to release many details on the suspects, including whether they were on any watch lists, but have indicated they believe the plot may have links to al-Qaida.

A senior U.S. counterterrorism official, who spoke on condition of anonymity because of the sensitivity of the issue, said Tuesday that none of the eight suspects was on any American lists that identify potential terror suspects.

One news report suggested the group could have been recruited by the head of al-Qaida in Iraq, but the British security official said that was “unlikely.” He said the investigation was not focusing on Iraqi links, other than the fact that one suspect was from Iraq.

Patrick Mercer, a legislator in the opposition Conservative Party who is a former British army intelligence officer, said he doubted the plotters came to Britain already planning the attack.

“I think these people came into the country, possibly already radicalized or certainly sympathetic … and the process of radicalization has been completed while they’re here. My inclination is to say that these are intelligent and highly motivated people, so the probability of self-radicalization is higher,” he told the AP.

Ayres, the American security expert, said he doubted the group had “direct contact” with an outside group like al-Qaida, saying they would not have needed any serious training for the plot that was carried out. “The attack vector that they used wasn’t very sophisticated,” he said.

But Mercer said from what he had heard from his sources, the plotters did attempt a complex assault. He said the first car bomb outside the Tiger Tiger nightclub was intended to draw people out from other pubs and nightspots, when the second bomb was to be exploded.

“It’s not the most sophisticated attack on earth, but I would suggest it’s not something by a bunch of medical students – there’s military thinking behind this – so there will have been, I’m pretty sure, a guiding hand,” Mercer said.

That is exactly what investigators are still trying to piece together, the security official said.

“When did they first meet? Did they meet in Britain or overseas? Were they sent here? Is there an actual al-Qaida link? They are questions we’re looking for answers to,” the official said.

Associated Press writers Rob Harris in Runcorn, England; David Stringer in London; Ben McConville, in Glasgow, Scotland; Lara Jakes Jordan in Washington; and Shafika Mattar and Dale Gavlak in Amman, Jordan, contributed to this report.

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