Friday afternoon, police and agents with the FBI's Terrorism Task Force searched her house in Yeadon and another location in West Philadelphia associated with Archer.
Investigators are scouring Archer's Internet activity to see if he may have had contact with ISIS members or other radical Islamic groups. A law enforcement source said late Friday that so far they had not found any indication that Archer had been in contact with known terrorism suspects.
Federal authorities are also looking into two trips Archer made to the Middle East. In the fall of 2011, he traveled to Saudi Arabia for a pilgrimage to Mecca and stayed for several weeks, an FBI spokesman said. The next year, he went to Egypt for reasons that are unclear and spent several months there.
"We will see where the investigation leads us," said Philadelphia Police Commissioner Richard Ross, who is in his first week on the job.
Meanwhile, police praised the bravery of the wounded officer, Jesse Hartnett, who was shot three times in an arm but still managed to pursue and wound Archer as he fled the scene of the shooting at 60th and Spruce Streets. The officer, 33, was in critical but stable condition Friday.
It was extraordinary, Ross said, that Hartnett had survived.
"This guy tried to execute the police officer," the commissioner said in a predawn briefing on the shooting. At a news conference Friday afternoon, he said of the officer: "The bravery he demonstrated was absolutely remarkable."
Local and national officials condemned the attack.
Mayor Kenney called Archer a criminal and said his actions were no reflection on Islam.
Jacob Bender, executive director of the Philadelphia chapter of the Council on American Islamic Relations, said the incident "should not be seen as representative of Muslims or the faith of Islam," and called for a thorough investigation of the shooting.
Hartnett, an 18th District officer with five years on the force, was patrolling alone on 60th Street when Archer strode toward his cruiser around 11:40 p.m. Thursday.
Archer was armed with a semiautomatic 9mm pistol - a police-issued firearm that had been reported stolen from an officer's home in 2013, Ross said. He said it was unclear how Archer got the gun.
In video of the shooting obtained by The Inquirer, Archer was captured walking toward Hartnett, his arm extended, firing shot after shot and pocking the cruiser with bullets.
Then, he leaned into the officer's squad car and opened fire again before sprinting back down the street.
Hartnett was hit three times in the arm. Bleeding heavily, his arm limp, he struggled out of his car and managed to run after Archer and fire back, wounding him.
'Shots fired! I'm shot!'
Over the police radio, officers heard Hartnett's frantic voice as he called for help: "Shots fired! I'm shot! I'm bleeding heavily."
The first officers to arrive on the scene hurried Hartnett into a police car - "a scoop and run," said one officer on the scene - and rushed him to Penn Presbyterian Medical Center.
"There was blood everywhere on the street," the officer said.
A block away, at 60th and Delancey Street, another group of officers captured Archer, who had been shot once in the buttocks. His gun lay next to him, with the slide locked, the officer said - Archer had fired every bullet in his gun.
Hartnett suffered a broken arm and nerve damage, and has "a lot of recovery ahead of him," Ross said.
Archer was taken to the Hospital of the University of Pennsylvania, and then to the homicide unit, where detectives were interviewing him late Friday.
Clark said Archer repeatedly professed his allegiance to the Islamic State in his confession. Ross said Archer told investigators he believed police enforced laws counter to the Quran.
"He doesn't appear to be a stupid individual, just an extremely violent one," Ross said.
Reached at her home in Yeadon, Archer's mother, Valerie Holliday, said he was the eldest of seven children.
He had lifelong ties to Philadelphia, a former lawyer, Doug Dolfman, wrote in court papers, and had attended Cheyney University and worked in the city as a security guard.
Holliday said her son had suffered head injuries from playing football and a moped accident.
"He's been acting kind of strange lately. He's been talking to himself . . . laughing and mumbling," she said. "He's been hearing voices in his head. We asked him to get medical help."
She said her son is a devout Muslim who has practiced the faith for some time. She said he believed he had been targeted by police.
"I don't know how he got the gun," she said. "I'm still hoping they have the wrong child."
Members of the FBI's Terrorism Task Force converged on Holliday's home on Friday afternoon. FBI agents left with a cardboard box and several evidence bags.
A relative said Holliday had left the home with police.
In recent years, Archer was arrested in Delaware County and in Philadelphia. He was on probation at the time of the shooting.
In January 2012, Archer threatened another man with a gun at a house on Alden Street, near 57th Street and Spruce, in West Philadelphia.
Sometime after that incident, Archer traveled to Egypt. When he returned to the United States in December 2012, he was taken into custody by New York authorities because of his outstanding arrest warrant in the gun case.
In March, Archer pleaded guilty to simple assault and carrying a gun without a license, and was sentenced to nine to 23 months in jail and two years' probation. He was already out on bail, and was immediately paroled.
Archer is awaiting sentencing in a 2014 case in Delaware County, where he was charged with forging documents, careless driving, driving with a suspended license, and other offenses. He was found guilty in November and was scheduled to be sentenced Monday, according to court records.
Hartnett's family learned around midnight that he had been wounded.
Robert Hartnett, who spent the night at the hospital at his son's side, said his son's survival was "a miracle."
Hartnett served 14 years with the Coast Guard, joining shortly after Sept. 11, 2001, and serving on active duty through August 2008. Afterward, he served in the Coast Guard Reserve, and spent two years on the East Lansdowne police force before becoming a Philadelphia police officer.
Colleagues said Hartnett was widely respected as a humble but hardworking officer. And he was compassionate, Ross said, once buying dinner for the son of a drug suspect he had just arrested.
"He has good determination, and he's always wanted to help people and be a policeman," Hartnett's father said.
Philadelphia police officers took to social media to express support for their wounded colleague and decry the attack.
At Friday's news conference, Kenney said the shooting showed the sacrifices officers make and highlighted Philadelphia's problem of gun violence.
"There are too many guns on our streets," he said.
Gov. Wolf issued a statement denouncing the shooting as an ambush and saying, "This alleged intentional act of violence against an officer seeking to help a fellow citizen is horrifying and has no place in Pennsylvania."
Sen. Robert P. Casey (D., Pa.) called the shooting "an act of barbarism," and said he was pleased that federal authorities were working on the case with local police.
"Those who carry out attacks in the name of ISIS or any other terrorist organization must be fully prosecuted," he said, but added: "This individual and any who would advocate similar acts are not representative of any religion - they are thugs and criminals."
Rep. Patrick Meehan (R., Pa.) praised Hartnett's "tremendous heroism" and said he found Archer's statements about the Islamic State "troubling," and called for federal investigators to investigate any possible ties to "overseas radical groups."
Officers in Hartnett's district were shaken, one of his colleagues said.
"It's crazy to know there are people who don't even say anything to you, who just walk up and empty an entire magazine into your car," that officer said.
But he said he and his unit would not be deterred from doing their jobs.
"We might be a little nervous for a while, but we're going to do our job and help people who need help," he said. "That's just what we do."
Contributing to this article were staff writers Emily Babay, David Gambacorta, Mike Newall, Julie Shaw, Dylan Purcell, Michael Matza, and Joseph A. Gambardello.