LONDON >> He was quiet and withdrawn, a college dropout who liked soccer — and, some say, showed alarming signs of being radicalized years before he walked into a pop concert at Britain’s Manchester Arena and detonated a powerful bomb, killing himself and 22 others.

While some claim Salman Abedi had been banned from the mosque he attended for statements glorifying terrorism and his angry rhetoric even prompted an acquaintance to report him to the authorities, others deny that account, saying he never showed any worrying or erratic behavior.

The son of Libyan parents who immigrated to Britain in the early 1990s, Abedi has been identified by British authorities as the bomber who attacked the Ariana Grande concert Monday night. While Home Secretary Amber Rudd said he was on the radar of the intelligence service “up to a point,” it was not clear how much attention officials had paid to his activities and whether authorities could have stopped him.

As a portrait of the alleged bomber emerged, it was complicated by contradictory accounts over whether Abedi held views that had sparked concern before Monday’s attack.

Mohammed Shafiq, who heads the Manchester-based Muslim organization Ramadhan Foundation, said some of Abedi’s past statements had prompted a Libyan community activist in Manchester to report him to the national counter-terrorism hotline two years ago.

“He was glorifying terrorism,” Shafiq told The Associated Press. “His extremism, his rhetoric, was an issue of concern, so much that this person reported it.” He said he did not know the outcome of that call.

But Mohammed Fadl, a spokesman for Manchester’s close-knit Libyan community who knew Abedi’s family, said that Abedi appeared “normal” and he was not aware of any alarm bells sounding about him.

“There was definitely nothing too apparent or obvious,” Fadl said. “To my knowledge and many in this community, that’s the general impression. If we saw it we would have said something.”

Akram Ramadan, another member of the city’s Libyan community, said Abedi was banned from Didsbury Mosque after he confronted an imam over an anti-Islamic State sermon.

“There was a sermon about anti-Daesh,” Ramadan said, using the Arabic acronym for the Islamic State group. Abedi stood up and shouted at the imam, “‘You are talking bollocks.’ And he gave a good stare, a threatening stare into the imam’s eyes.”

Fadl rejected that account, though he conceded he did not witness the incident. He said that while Abedi’s family was well-known and respected — and his father even used to perform the call to prayers during the many years he lived in Manchester — Abedi himself was an unsociable young man who didn’t regularly attend mosque or community gatherings.

“He was very isolated. Always,” Fadl said. “Very few people in the community here were close to him and therefore Salman’s fanaticism wasn’t something the community was aware of.”

Still, Fadl said he had heard Abedi’s father took his son’s passport away over concerns about his close ties to alleged extremists and criminals.

“Even if the families knew about their sons’ ideologies or affiliations, they wouldn’t talk but keep it to themselves,” he said.

A relative in Libya said Abedi was driven by what he saw as unjust treatment of Arabs in Britain and was particularly upset by the killing last year of a Muslim friend whose death he believed went unnoticed by “infidels” in the U.K.

“Why was there no outrage for the killing of an Arab and a Muslim in such a cruel way?” she asked, speaking on condition anonymity over fears for her own safety. “Rage was the main reason,” for the blast, she said.

She said the suspected bomber was pained by the killing of Abdel-Wahab Hafidah, an 18-year-old who news reports say was chased by a group of men, run over and stabbed in the neck in Manchester in May 2016.

“They wouldn’t let you share bread with them,” she said Abedi told her. “They are unjust to the Arabs.”

Abedi’s father and two of his brothers have been taken into custody in connection with the investigation into the bombing. His older brother, 23-year-old Ismail, was arrested by Manchester police on Tuesday. His father, Ramadan, and another brother, 18-year-old Hashim, were detained a day later by Libyan authorities in Tripoli, where they now live.

Ramadan Abedi, who is alleged to have been a member of the al-Qaida-backed Libyan Islamic Fighting group in the 1990s — a claim he denies — told the AP before he was arrested that his son was not involved with the concert bombing and was not connected to the Islamic State group, which claimed responsibility for the attack.

That assertion clashed with information provided to Libyan authorities by Abedi’s brother Hashim and his mother, who was also brought in for questioning in Tripoli.

In a final phone call he placed to his mother and brother just before the attack, he purportedly told his mother: “Forgive me,” said Ahmed bin Salem, a spokesman for Libya’s anti-terrorism unit, the Special Deterrent Force.

“He was giving farewell,” bin Salem said.

He said Abedi’s mother also told investigators her son had left for Britain four days before the attack after spending a month in Libya. Based on the account of his younger brother, Hashim, investigators think Abedi used the internet to learn how to make a bomb and “seek victory for the Islamic State,” bin Salem said.

Much of Abedi’s background would seem to bely such a sinister trajectory.

Born and raised in Manchester, Abedi attended the Burnage Academy for Boys, a school with a large proportion of ethnic minority students, from 2009 to 2011. He went on to attend Manchester College and studied business at the city’s Salford University, though he didn’t attend classes there this academic year and never earned a degree, the institution said. An avid soccer player, he often met up with friends for pickup games.

Neighbors in Fallowfield, the south Manchester suburb where Abedi lived, recalled a tall, thin young man who often wore traditional Islamic dress. But few said they knew him well.

Alan Kinsey, 52, who lives across the street, said he would often see a young man in his 20s returning late at night. “I thought he worked in a takeaway or something” because of his late hours, Kinsey said.