GUANTANAMO BAY, Cuba - A Danish psychologist who believes Muslims are raised to be aggressive and that inbreeding has damaged their genes informed a damning expert opinion of the risk Omar Khadr poses to public safety, court heard Wednesday.

Under cross-examination by defence lawyers, Dr. Michael Welner said he talked to Nicolai Sennels before coming to the conclusion that the Canadian-born Khadr was "highly dangerous" — an opinion he gave Tuesday on the first day of Khadr's sentencing hearing.

Welner, a witness for the prosecution, said he admired Sennels for his work trying to help young Muslim inmates in Denmark and found him informative.

Sennels, who is based in Copenhagen, has written extensively on Muslims, including one article introduced into evidence Tuesday.

"If a Muslim does not react aggressively when criticized he is seen as weak, not worth trusting and he thus loses social status immediately," Sennels wrote.

In another article, Sennels, 34, attributed a host of problems within the Islamic world to intermarriage among first cousins.

"Massive inbreeding within the Muslim culture during the last 1,400 years may have done catastrophic damage to their gene pool."

Sennels has also stated that Muslim integration into western societies is not possible, a view Welner called "political."

The seven military officers on the jury will decide on a sentence for Khadr, who pleaded guilty on Monday to five war-crimes charges.

Although they can sentence him to life in prison, the actual sentence will be capped at eight years under a plea-bargain agreement, the details of which have not been disclosed to the jury.

Khadr would be returned to Canada after one more year in American custody.

Testifying for a second day, Welner found his credibility under attack as the defence hammered him for being selective in his depictions of Khadr.

Welner had testified on Tuesday that Khadr was only interested in the Qur'an, and had shown little interest in western literature.

However, during testy exchanges with defence lawyer Maj. Matthew Schwartz, Welner conceded Khadr had indicated little interest in the Qu'ran before being shipped to Guantanamo.

He also testified Khadr had in fact read books by South African President Nelson Mandela, U.S. President Barack Obama, and even romance writer Danielle Steele.

He qualified his view by saying Khadr's dangerousness lay in his ability to be "inspiring and be incendiary" to other radical Islamists.

Khadr, 24, who smiled and chatted with his lawyers, grew pensive as Welner testified, at times glaring at him.

Welner admitted that professional colleagues did not review his opinion to ensure a lack of bias.

It was also the first time he had assessed a radical jihadist for any risk to public safety.

After interviewing Khadr for seven hours earlier this year, Welner concluded that the detainee did not have any mental illness.

Later Wednesday, court heard three victim-impact statements.

Former special forces sergeant Layne Morris described how he was hit in the head by shrapnel during the 2002 raid on the compound where Khadr was captured.

He thought he had been shot and was "standing there dead," Morris testified, at times finding it difficult to stay composed.

"It was complete despair — I would not get to see my kids again."

Morris lost sight in one eye and he and Speer's widow later successfully sued Khadr's late father in a Utah court, winning a judgment in the tens of millions of dollars.

Two of Speer's close comrades described the special forces medic in glowing terms and his death as a "catastrophic loss," frequently pausing as they fought back tears.

The hearing continues Thursday.