The sign at the door of Masjid Mujahideen, the West Philadelphia mosque of accused ambush-shooter Edward Archer, is uncommon for a house of worship: "Please do not bring any weapons, guns, or knives into the masjid."
Carpeted wall to wall in forest green, the second-floor sanctuary of the former house on 60th Street near Osage Avenue drew 100 men to a recent Friday service. A floor below, 30 women prayed in a room with a loudspeaker.
They were a cross-section of African American converts to Islam: women in head scarves; men in skullcaps; laborers with names embroidered on work shirts; a teen in a hoodie branded "Straight Outta West Philly"; a gray-haired gent in pressed slacks; a twenty-something whose white robe covered his jeans, but not his house-arrest ankle monitor.
Here, where shoeless worshipers kneel in rows, Archer was an outlier.
"You'd see him sitting all alone," said his former father-in-law James Atkinson. "He'd dissociate."
Archer, 30, also known as Abdul Shaheed, is charged with attempted murder in the brazen Jan. 7 shooting that severely wounded Philadelphia police officer Jesse Hartnett.
Under questioning by detectives, police say, Archer confessed and said he shot the officer in the name of Islam.
"I follow Allah," he told investigators, according to Homicide Capt. James Clark. "I pledge allegiance to the Islamic State, and that's why I did what I did."
The mention of ISIS was explosive. It drew international media attention to Philadelphia, and a tweet of support for Officer Hartnett from GOP presidential contender Jeb Bush.
Fellow GOP candidate Sen. Marco Rubio of Florida condemned the shooting at a town-hall meeting in Aiken, S.C.
"There was a terrorist attack yesterday, in the city of Philadelphia. A terrorist attack," he said. ". . . This is the new face of the war on terror."
In a nation fearful of jihad on U.S. soil - and a month after an American Muslim and his wife slaughtered 14 people in San Bernardino, Calif. - the attempted assassination of Hartnett, 33, looked like a radicalized lone wolf spraying fire.
The mention of ISIS brought the swift deployment of the FBI's Joint Terrorism Task Force.
Although Archer's reported confession could be a deranged man's twisted rationale, federal authorities are investigating the case as a possible terror attack, FBI Director James Comey said.
Investigators are scouring Archer's Internet activity and phone records and studying his travel history in an effort to learn whether he might have had contact with ISIS or other terrorist groups. Comey said his agency was "working very hard to understand this guy's entire life."
That means building a psychological profile; poring over evidence from places Archer lived in Yeadon and Philadelphia; and interviewing relatives, friends, and associates.
On the night of the shooting, surveillance video captured the ambush in chilling clarity. The video shows a man in a mask and white robe firing repeatedly at Hartnett's patrol car. The gunman rushes up, thrusts his gun into the car, empties the clip, and flees.
Bleeding profusely from his left arm, Hartnett returned fire. A lightly wounded Archer was arrested around the corner.
The drama struck a nerve.
It "sheds light on the threat ISIS, and those inspired by its extremist ideology, pose to law enforcement," said Nancy Baron-Baer, Philadelphia chapter director of the Anti-Defamation League, a civil-rights group.
"The majority of Muslims are peaceful," Philadelphia lawyer George Parry, a former state and federal prosecutor, wrote in an op-ed published in The Inquirer. "But the intentions of the majority are utterly irrelevant [to] the presence in our midst of an extreme and bloodthirsty Muslim minority."
Clint Watts, a homeland security expert with the Foreign Policy Research Institute in Philadelphia, is skeptical of Archer's purported motive.
"This is headline-inspired, not ISIS-inspired," Watts said. "It tends to happen after a successful attack, like what happened in Paris. People who already have psychological issues pick up a weapon and decide to act. It's more personal than ideological."
An attacker, Watts said, could be someone who has harbored hostilities for a long time and reinvents himself as an ISIS follower "to make his act seem more prolific and valuable."
Although a preliminary investigation suggests that Archer acted alone, investigators continue to probe his activities, interpretation of Islam, and overseas travel, including two visits to the Middle East.
For American Muslims, the pilgrimage to Mecca in Saudi Arabia can be the most challenging of the "five pillars" of religious obligation. A round trip from the East Coast costs about $5,000.
Archer apparently had help from a "lending circle" when he made the pilgrimage, or hajj, in 2011.
He participated with a small group of men who met to watch and play sports and pooled resources in a fund that offered members one-time aid to fulfill the once-in-a-lifetime duty to pray at Mecca.
"They'd have dinners and all donate," said Mujahideen's imam, Asim Abdur Rashid, 64. "I guess they decided it was [Archer's] turn" in 2011. "I guess he saved his little money, too."
An acquaintance who asked not to be identified spoke intimately about Archer and said his trip to Mecca had a calming effect on a man who sometimes seemed disorganized, with a spotty employment record in construction and private security, and as a utility company subcontractor.
A day after the shooting, Archer's mother, Valerie Holliday, of Yeadon, told The Inquirer that Archer is the eldest of seven children, attended Penn Wood High School in Yeadon, and began practicing Islam in his early 20s.
Court records indicate he completed two years at Cheyney University.
Holliday said her son suffered multiple head injuries playing football and in a moped accident, events that could contribute to mental instability. She downplayed any connection between his Islamic faith and the shooting.
"He's been acting kind of strange lately" she said in the January interview. "Talking to himself . . . laughing and mumbling . . . hearing voices in his head. We asked him to get medical help."
Archer's defense lawyer, Trevan Borum, said he is "investigating the facts and circumstances surrounding the case," including Archer's activities in the months before the shooting. A preliminary hearing in Municipal Court is scheduled for March 10.
Rashid, the imam, said he had never spoken with Archer but would like to.
"I would ask, 'Did you do it to hurt the Muslim community?' " Rashid said. " 'Because you surely didn't think it was some noble thing that would elevate us.' "
Qasim Rashad, 54, chairman of United Muslim Masjid, a Center City mosque, said he met Archer through a friend in the lending circle.
Rashad said Archer was devout; seemed genuinely interested in Islam; and founded an inter-mosque flag football league, which played at the Morris Recreation Center at 58th and Spruce Streets.
"He wanted to develop good relations between the mosques," Rashad said. As commissioner of the league, he also encouraged non-Muslims to play. "He was not a thug. . . . I believe something happened to Shaheed, mentally. And because of [that], he made connections between what he did and the Islamic State. The person I knew would not have done that."
Acquaintances say that whatever changed or was revealed in Archer's character happened just before he moved to Egypt in 2012, telling friends he was going there to study Arabic.
A month before that eight-month sojourn, a man later identified in court records as Archer was accused of using a gun to threaten a West Philadelphia man.
In an interview, James Atkinson said his daughter was married to Archer for about two years before the couple separated around 2010. Then, Atkinson said, her second marriage turned tumultuous.
Court records show that Atkinson, along with Archer and another man who wore a long beard and Muslim robe, drove to West Philadelphia in January, 2012, grabbed the second husband, ordered him to "stop bothering" the daughter, and threatened him at gunpoint.
A week after that happened, Atkinson was charged with assault and making terroristic threats. A warrant for Archer's arrest was issued a month later, but by then he had left for Egypt.
Acquaintances said Archer's time there was soured by racist comments directed at his nationality and skin color. There came a point when he desperately wanted to come home. On Dec. 2, 2012, he did.
After landing at John F. Kennedy International Airport in New York, he was arrested on an outstanding warrant for the gunpoint assault in Philadelphia.
He spent five months at Riker's Island before his case was transferred to Philadelphia.
Lawyer Doug Dolfman negotiated his bail.
In an interview, Dolfman remembered Archer as "impulsive, arrogant," and unappreciative, even after Dolfman got his $500,000 bail reduced by half.
"I had no indication he was radicalized by ISIS or any other organization," Dolfman said. "I think he is somebody who decided to raise that flag now, to put fuel on the fire," and see where it leads.
Last March, Archer pleaded guilty to simple assault and carrying an unlicensed gun. With credit for the time he spent in prison, he was freed on parole.
Tens month later, police say, he was the man at 60th and Spruce Streets, rushing forward in a flapping white robe, spraying wild fire at Officer Hartnett.
Staff writers Mari Schaefer, Joseph A. Slobodzian, Aubrey Whelan, Jeremy Roebuck, and Julie Shaw contributed to this article.