The Somali immigrant, who moved to the "Land of 10,000 Lakes" when he was 8, had good grades at the University of Minnesota and called Muslims to prayer at his mosque, where he also slept during the holy month of Ramadan.
But on Nov. 1, Hassan disappeared, as have a dozen other boys and young men here — two days after another young Muslim from Minnesota blew himself up as a suicide bomber in Somalia.
Hassan, 18, called his grandmother to say he was back in Somalia, where an Islamist militia is trying to take over the Horn of Africa nation. What he was doing there, he did not say.
Now the FBI is asking questions, as are members of the Somali community. The Abubakar As-Saddique Islamic Center denies any wrongdoing, but many here suspect that the mosque and its imam are radicalizing their youth to become jihadists in an Islamic holy war overseas or perhaps even in the United States
"They are very powerful, whoever got into his mind and got him to do this," says Hassan's grandmother Fadumo Elmi, 83. "We were forced out of our country one time. We don't want to be forced out of here."
Details of the disappearances are few, but what little is known is cause for concern, says Abdizirak Bihi, a community activist who represents six families of young men who disappeared in early November.
Among them was Bihi's nephew, Burhan Hassan, 17, a high school junior.
All were good students, had no problems with the law, Bihi says. All were raised by single mothers and spent a lot of time in the Abubakar As-Saddique Islamic Center.
The center is the largest mosque in the Twin Cities. Bihi worries it is preaching a radical Islamic ideology to vulnerable young men.
Shirwa Ahmed, 19, who left in August with no notice to his family, was among five terrorists who blew themselves up Oct. 29 in an attack that killed 24 people in Somalia, Bihi says.
"We are wanting the government and politicians to investigate who is responsible for sending our kids and we are requesting the American government to help us to get us back our kids." Bihi says.
Other Somali immigrants worry the disappearances may foretell dangers for their adopted nation. "That kid that blew himself up in Somalia could have done it here in Minneapolis," says Omar Jamal, executive director of the Somali Justice Advocacy Center in St. Paul.
Special Agent E.K. Wilson of the FBI in Minneapolis would not say whether his agency is investigating the mosque. Bihi and Elmi said the FBI has talked to them and others about the missing.
Wilson said the FBI knows that Muslims here have been going overseas to fight.
"We're aware that a number of Somali men have traveled from around the United States including Minneapolis to potentially fight overseas," Wilson said.
A lawyer for the Abubaker As-Saddique Islamic Center denied any involvement in planning or financing the men's travels or any political indoctrination.
"The mosque has taken a position that it would never take a stand on any political issues," says lawyer Mahir Sherif in San Diego. "We do not support terrorism or any kind of suicide bombing or act of violence."
He said federal authorities last month prevented the mosque's religious leader, Sheik Abdirahman Ahmed, from flying to Mecca.
Somalia has been plagued by lawlessness, terrorism and warfare since the collapse of the military government in 1991. In recent years, a radical Islamist militia that seeks to impose Islamic law captured the capital of Mogadishu, where 18 U.S. soldiers died in the infamous "Blackhawk Down" battle of 1993. Troops from Ethiopia invaded in 2006 to counter the Islamists, who have been praised by Osama bin Laden.
Yusuf Shaba, who writes about Islamic ideology and radicalism for the Warsan Times, a Somali-English monthly newspaper published in Minneapolis, says he decided to speak out about what he considers Islamic indoctrination at Minneapolis mosques because he doesn't want his sons to follow the same path he did.
Shaba, 34, joined Al Ittihad Al-Islami (Islamic Union) at age 16 and was wounded at age 19 in Somalia. Al Ittihad was Somalia's largest Islamic terrorist group in the 1990s.
Shaba says jihadists generally recruit young men from among two groups: those shunned by their families because they've turned to drugs, gangs or alcohol; and the sons of families who forbid exposure to Western culture and allow them to socialize only at the mosque.
Shaba says he and his three teenage sons attended a program two months ago at Abubaker As-Saddique Islamic Center, where a former Somali warrior sat in a circle with other young people and delivered a passionate recitation of his experiences during the Somali civil war.
Some mosques also screen videos about the war in Afghanistan and about Muslim victims of perceived injustices in such places as Nigeria and the Palestinian territories. "They give them all the grievances that Osama Bin Laden has," Shaba says. "They talk about nothing but jihad and it's the best thing that can happen to a Muslim."
When the brainwashing is done and the teachers are confident students will do anything asked of them, the teachers give them tazkia, or clearance, to get more specialized training in the United States or abroad, Shaba says.
"The people who trained us encouraged us to not get married, to sever our ties with our families, so that when the mission comes we won't worry about family."
Shaba says similar activities occur at Minnesota Da'wah Institute in St. Paul, another mosque. Sheik Mahamud Hassan, the institute's imam, says nothing like that is happening as his mosque. "It's liars," he says. "I'm not missing any members."
Elmi wrapped herself in her shawl and sobbed as she thought of Hassan in her one bedroom apartment in a Minneapolis public housing high rise. Outside, snow covered the parking lot and temperatures were below zero.
They moved to the United States in 1996, when Hassan was 8 and after his father was killed in the civil war. Hassan was obedient, but after going to the mosque, "He was completely changed."
"I thought the mosque would be a much safer place than the night clubs and bars," she said, crying. "I don't want God to curse me because I say something bad about the mosque."