Dahir Adan had been acting strangely before he stormed into a Minnesota mall and stabbed nine people, according to two Somali community leaders who are in contact with his family.
A picture began to emerge Monday of the 22-year-old private security firm employee, who was shot dead during his alleged stabbing rampage Saturday.
But authorities are still working to piece together the suspect's background and pinpoint his motive, St. Cloud Police Chief William Blair Anderson told reporters.
"We are trying to find everything," Anderson said. "I want to know everything about this man, from the day he was born until last Saturday."
Federal law enforcement sources and Somali community leaders identified Adan on Monday.
An ISIS-linked news agency praised him as a "soldier of the Islamic state."
CNN hasn't independently verified the claim, and on Monday, authorities maintained that the suspect appeared to have acted alone.
"We haven't uncovered anything that would suggest this was anything but a lone attacker at this point," Anderson told reporters.
The FBI is calling the attack "a potential act of terrorism." But no evidence has been found tying the suspect directly to terror groups, the police chief said.
Following the Saturday stabbings, Lul Hersi stood outside the Crossroads Mall, waiting to find out if her son was among the victims.
Fear washed over the Somali-American mother, not just for her son's well-being, but also because of the potential backlash against her community.
"This has been a dark day; it is a day we will never forget," said Hersi. "ISIS does not represent us. It does not represent Islam, and it does not represent Somalis."
Over the weekend, local newspapers in Minnesota, including the Minneapolis Star Tribune and St. Cloud Times, identified the attacker as a member of the Somali community from the central part of the state.
St. Cloud, a 67,000-person town about 65 miles northwest of Minneapolis, is home to one of Minnesota's larger immigrant Muslim communities. In recent years, the community there has faced conflicts with other Minnesota residents, including incidents that have led to damage to mosques and opposition toward at least one new house of worship, according to the StarTribune.
In response to this weekend's stabbings, members of the Muslim and Somali communities held a news conference Sunday to mourn the victims and call for unity.
"We are also concerned about the potential backlash," said Jaylani Hussein, executive director of the Council on American-Islamic Relations chapter in Minnesota. "We understand in St. Cloud there is more anti-Muslim organizing, and we hope they do not use this incident to divide (our community)."
Ahmed Said, executive director of the Somali American Relations Council, said it remained unclear if religion motivated the attack.
Somali community: Let's spread love instead of hate
In recent years, federal investigators have tracked the recruitment of potential ISIS fighters in Minnesota. Since 2014, nine Somali-Americans from that state were either convicted at trial or pleaded guilty in a plot to join ISIS by traveling to Syria. Before that, dozens of male Minnesota residents had left to join Al-Shabaab, a terrorist group working to turn Somalia into an Islamist state.
Mohamoud Mohamed, a spokesman for the Central Minnesota Islamic Center in St. Cloud, said at the Sunday news conference the Muslim community in central Minnesota has no ties to any Islamic terrorist groups.
"We are the victims of those terrorist groups," he said. "Islam is peace."
Police and witnesses said the attacker, wearing a private security company uniform, entered Crossroads Mall on Saturday night around 8 p.m. CT. Inside the mall, he made a reference to Allah and asked at least one person if they were Muslim before he attacked.
Ashley Bayne, an employee of J.C. Penney at the mall, was visiting a coworker at the time of the incident. When the stabbings began, Bayne ran out to the parking lot and took off in her car, crying and shaking in the aftermath of an event she never thought would happen there.
"All of sudden chaos just broke out," Bayne told CNN. "There was a bunch of people running into the J.C. Penney mall entrance, and they were just screaming that someone was going around the mall stabbing people, and that there was blood everywhere."
Though the mall's security teams were on site, the security officers were not armed.
Of the nine people stabbed, St. Cloud Mayor Dave Kleis said, three people were still hospitalized, including one person who remains in life-threatening condition.
The stabbings took place in several locations within the mall.
Amid the chaos, Jason Falconer, an off-duty police officer from nearby Avon, killed the suspect as he threatened other shoppers.
Authorities said Adan, the attacker, had three previous encounters with police. According to Anderson, most of the encounters were for minor traffic violations, none of which led to an arrest. The police chief declined to provide further details about the attacker until more information was known.
At a news conference Sunday afternoon, the mayor and police chief praised Falconer, a part-time officer and former police chief of Albany, Minnesota, for taking action. Both officials said they had viewed a surveillance tape from Macy's which revealed details of the confrontation.
"His heroic actions are exemplary of having witnessed what he did as the suspect was lunging at him with a knife," Kleis said. "Not only did he fire, the suspect went down, came back up on three different occasions. He protected others from being injured and potentially loss of life. Clearly, a hero."
St. Cloud mayor: "Off-duty officer, Jason Falconer, who shot attacker was a hero."
3 of 9 stabbing victims were hospitalized. 1 victim has life-threatening injuries.
The Crossroads Mall was expected to reopen Monday. Beyond that moment, though, Anderson said the attack will change the city forever.
"Whenever something as awful as this happens, it's hard for things to be the same as they were," the police chief said.
The mall stabbing was one of several incidents reported nationwide Saturday. In New York City, an explosion ripped through the Chelsea neighborhood, leaving 29 injured. A second explosive device was found a few blocks away, authorities say.
In New Jersey, an explosion went off in a garbage can on the route of a Marine Corps charity run. Thousands of people were about to participate in the 5K race in Seaside Park. No injuries were reported.
After the attacker in Minnesota was killed, the police chief said two search warrants were executed at an address in St. Cloud, and the suspect's vehicle was impounded. Though the case may be closed soon, Anderson didn't see things going back to normal.
For Hersi, she simply hoped the tragedy would bring St. Cloud residents together — rather than divide them further.
"Let us unite as one Minnesota," she said. "Please let's spread love instead of hate."