Mystery Terrorist: The Unknown Life and Violent Times of Illegal Border-Crosser Sidi Mohammed Abdallahi

Missed Warning Signs and Unanswered Questions Surround Abdallahi’s Violent Path to Terrorism in Chicago, Highlighting Critical Gaps in Border Security and Investigative Transparency

This article is part two of a three-part series.
Read part one here.
The apartment Abdallahi shared with other illegal Mauritanian border crossers in South Chicago.

The apartment Abdallahi shared with other illegal Mauritanian border crossers in South Chicago.

Todd Bensman

If ever there was a magic moment for Americans to learn why Mauritanian national Sidi Mohammad Abdallahi rampaged through an Orthodox Jewish neighborhood firing a semi-automatic handgun at Jews and police, trying to rack up a body count, it was after he’d been dead a week on December 6, 2024.

“Prayers will be held over the body of the deceased” at 8:45 pm, read a post on the Chicago Mauritanian Community’s Facebook page. “Notice: Everyone is requested to come and pray for our bereaved. It is our right. Let us not forget also the virtue of a funeral, its follow-up and rewards.”

The funeral post drew several responses from the account’s 537 followers and drew one re-share.

“May God have mercy on him,” wrote Vadel Wel Belli, an active group member.

The 22-year-old Abdallahi, critically wounded then arrested by police, had hanged himself the week before while in the Cook County Jail while awaiting his eventual trial on state terrorism and other charges for conducting an October 26 shooting melee described at length in Part 1 of this series. (See First Blood: Anatomy of a Border-Crosser’s Chicago Terror Attack).

The pre-trial jailhouse suicide had made perfunctory news headlines, but any reporter who would have attended the Chicago Mauritanian Community’s publicly advertised “prayers…over the body of the deceased” and presumed burial of Abdallahi on Friday, December 6, could have potentially interviewed the people who knew him most intimately. A Facebook page that matches Abdallahi’s full name, devoid of entries other than a photo of a car, show five followers, among them some who follow the Chicago Mauritanian Community. But no reporters bothered to show up, missing what turned out to be a consequential opportunity to learn about Abdallahi’s violent path from the Mexican border to the West Rogers Park neighborhood, which he shot up during his 20-minute attack.

No reporters bothered to show up, missing what turned out to be a consequential opportunity to learn about Abdallahi’s violent path from the Mexican border to the West Rogers Park neighborhood, which he shot up during his 20-minute attack.

A Center for Immigration Studies (CIS) trip to Chicago two weeks after the funeral service, to learn what the cancelled trial might have revealed about the ground-breaking first charged terrorist attack by a border-crossing illegal immigrant, discovered a window onto Abdallahi’s world in Chicago.

A Pakistani man who parks several black hearses at what turned out to be a large Albanian mosque at the provided Facebook address, one of which displays a “Muslim Funeral Service” sign in a window, told CIS that Abdallahi had “relatives” in the area, the first known reference to that. They were the ones who accepted the body from the county Medical Examiner’s office and paid for the funeral service, he said.

The Pakistani funeral director refused to say anything more without the family’s permission, which he offered to secure for CIS. They never responded.

The Chicago Mauritanian community’s self-described leaders, many of them recent immigrants like Abdallahi, declined CIS interview requests to talk about Abdallahi, through an interlocutor who works closely with them.

And so, even the most basic information of homeland security value about Abdallahi and his path to violence, essential in helping authorities uncover violent plans by other illegal border-crossers from countries of terrorism concern like Mauritania, remains out of reach. It has already been reported that his phone and computer searches showed he was steeped in jihadist and pro-Hamas propaganda – and wore to his attack a green workman’s safety vest currently popular among pro-Hamas demonstrators. But that’s a small morsel.

One of the first of many rounds Abdallahi fired during the 20-minute spree went through a Jewish man’s back as he walked to synagogue and more toward police until officers critically wounded him. That white-knuckled morning of terror left Chicago’s Orthodox Jewish community deeply shaken and, with no trial coming, feeling an unrequited ache to know how this young foreign gunman was ever able to cross the U.S. southern border and attack their people with a semi-automatic pistol while screaming “Allahu Akbar.”

They still didn’t know two months later – and won’t ever, at least not from any trial.

“When they said ‘terrorism,’ it was just kind of shocking. It made us wonder if there’s much more to the story, that this guy wasn’t just some guy,” Abdallahi’s Jewish victim, who has fully recovered, told CIS in late December. “Like, what are we missing from this story? No one has given us any details or answers or anything.” (The victim spoke to CIS, in his first and only interview, on condition that his identity not be disclosed for fear of future targeting.)

Many other questions hover over the incident unanswered but needed to enhance national security. For instance, did U.S. Border Patrol and U.S. Immigration and Customs Enforcement (ICE) miss opportunities to detect his extremist ideology at the border or later on?

“The safety piece is what’s scary,” he continued. “Like was he alone in this or was there somebody who coerced him to this? And if that’s the case, then okay, where are the rest of them and are they going to start infiltrating our neighborhood in some way? We still don’t have that answer, and that’s the scary thing.”

Many other questions hover over the incident unanswered but needed to enhance national security.

For instance, did U.S. Border Patrol and U.S. Immigration and Customs Enforcement (ICE) miss opportunities to detect his extremist ideology at the border or later on?

When Abdallahi crossed and passed a database check, was he ever detained and referred to the Border Patrol’s Tactical Terrorism Response Team or to ICE intelligence officers for extended terrorism-related interviews? That is supposed to happen with “special interest aliens,” who get assigned that tag if they hail from designated countries of terrorism concern like Mauritania.

According to material obtained by CIS through a Freedom of Information Act request, Border Patrol apprehended 18,260 Mauritanians (and hundreds of thousands of other special-interest aliens) who have illegally crossed the U.S. southern border from 2021 through December 2023, probably far too many for tedious direct interviews that can turn up signs of extremist beliefs.

If mistakes with Abdallahi remain unexplored, how then would the border agencies learn to interdict other potentially dangerous border-crossers already in the United States for a year or two?

Are co-conspirators who helped him or failed to report his plan still free or ruled out?

How exactly did Abdallahi, an illegal immigrant barred from obtaining a firearm in gun-restricted Chicago, get his hands on one and who might be held responsible?

What Is Known

ICE officials have confirmed that Abdallahi crossed the U.S. southern Border from Tijuana to San Diego on March 29, 2023. After a criminal and national security database check returned nothing derogatory, U.S. Border Patrol freed him on his own recognizance just as they have millions of other illegal entrants under orders from the Biden-Harris Department of Homeland Security.

Most often, those millions released were given dates to voluntarily report to ICE offices in their chosen destination city to file asylum claims or seek other forms of relief from deportation.

It’s unknown whether Abdallahi reported to ICE in Chicago or what the office knew of him. CIS has filed a Freedom of Information Act request to find out what ICE knew of him and when, if anything, but he may have obtained work authorization because Cook County prosecutors said at his detention hearing that he worked at a Chicago Amazon warehouse, and he had possession of a car where police found his phone after the shootout.

One of many obvious signs posted inside Midwest Sporting Goods gun store and range warns customers that they must have a state permit to touch a weapon.

One of many obvious signs posted inside Midwest Sporting Goods gun store and range warns customers that they must have a state permit to touch a weapon.

Todd Bensman

The Gun Mystery

The phone contained more than 100 “antisemitic and pro-Hamas” images and videos, the prosecutor said. He’d used the phone to map local synagogues, including one just a couple of blocks from where he attacked the Jewish man. And his Google search history included a gun store in the suburb of Lyons.

The Jewish victim he shot said he dearly wants to know how his assailant got the gun.

So CIS visited the Lyons gun store and shooting range that came up in one of Abdallahi’s searches, Midwest Sporting Goods, and pretty much ruled out that he obtained the firearm there. The store’s manager said detectives came around too and found that there was no record that Abdallahi held a state-required FOID card permit required to legally buy, sell, or fire any handgun in Illinois – a rule the gun store rigorously enforces to stay out of trouble. There also was no evidence that Abdallahi might have come in with a friend who had the permit, she said.

It could have been stolen and sold on the black market. Whatever the handgun’s history, the manager noted, police probably know a lot about it since they recovered it after the attack.

Home Life and Times

At least for a time, Abdallahi lived in a crowded but somewhat renovated South Chicago flop house above a taco shop shared by five other young Mauritanian immigrants who also crossed the southern border.

The apartment in a dilapidated older neighborhood pockmarked by abandoned condemned buildings consisted of three disheveled bedrooms with two men in each, a kitchen and toilet facilities. A prayer rug was visible on the floor in one room. No one seemed interested in replacing the expired batteries on two chirping smoke detectors.

Two of Abdallahi’s former roommates confirmed that Abdallahi had lived there for a time and had relatives in the area, including a “cousin” who spoke good English but that they hardly knew Abdallahi well enough to meaningfully comment. CIS could not locate the relative.

“Yeah, he lived here. Yeah. Yeah. Yeah,” one young Mauritanian named Abdullah, who crossed the southern border in 2023, said in broken English. Police interviewed him a couple of times. “But I’m not talking to this guy. I not see this guy. I don’t know about this.”

But Abdullah was definitive in saying that Abdallahi had never served in the Mauritanian military and also was angry about Israel’s war on Gaza as many in the community are.

“Too much Palestine! America give you everything to help you. Why do you have to go catch somebody outside of Palestine?” the young man opined.

A second Facebook page registered to Abdallahi’s unique name, recently taken down, showed that he had about 30 followers, most of them in Mauritania. Interestingly, Abdallahi followed the California Highway Patrol page in El Cajon, which is near the Mexican border.

Meanwhile, no one and no government agency seem interested in anything but moving on.

The FBI Closes Its Case; Other Agencies Fall Silent

Basic information to enhance public safety may remain unknown even to the most relevant federal law enforcement agency that investigates all suspected U.S. terrorism offenses, the FBI.

In this one rare instance, the FBI appears to have substantially ceded its role as primary investigator to the Chicago Police Department and Cook County Attorney’s office, which are arguably far less equipped for complex international and national terrorism cases even though they eventually lodged a state terrorism charge.

Basic information to enhance public safety may remain unknown even to the most relevant federal law enforcement agency that investigates all suspected U.S. terrorism offenses, the FBI.

Two days after his attack, the only peep from the FBI came in a written statement that it would work “diligently with local, state, and federal partners to provide critical resources and assistance as we learn more.” The bureau disappeared after that, steering clear of the few press conferences that local authorities staged.

In response to a more recent inquiry by CIS, the FBI now says it has closed whatever support case it had opened, since the suspect is dead, and declined CIS interview requests to rule out or in co-conspirators or foreign direction or anything else that is important to know.

“It is common for investigations to be closed in conjunction with the US Attorney’s Office if a subject dies prior to the conclusion of an investigation,” the FBI’s Chicago Public Affairs Team wrote to CIS in a January 3 email.

CIS has filed a federal Freedom of Information request to the FBI for more information and is prepared to litigate it if necessary.

The FBI’s tack here is highly unusual in the annals of obvious U.S. terror attacks, regardless of body count.

Contrast this lack of curiosity with the recent New Years Day vehicle ramming attack in New Orleans, which killed 14 plus the driver, and the so-called “cybertruck” bombing in Las Vegas, during which nobody died but the driver. Even before a full news cycle passed, news media brimmed with exhaustive reports about the life and times of a U.S.-born terrorist who carried out the ISIS-inspired New Orleans attack. One reporter even took social media followers on a video tour inside the dead terrorist’s FBI-searched Houston residence, before his victim’s bodies were even cleared from the bloody scene.

Even with Abdallahi dead and the trial cancelled, both the Chicago Police Department and the Cook County prosecutor declined CIS interview requests for interviews about the case. CIS has filed numerous FOIA requests.

Short of congressional or Trump White House intervention on behalf of transparency, the FOIAs may hold the last hope that authorities can improve processes and interdict other illegal aliens raised in countries where extremist ideologies are common and who might be predisposed to also plan mass casualty violence.

Todd Bensman is an editorialist, media commentator, and investigative author of the 2023 book OVERRUN, How Joe Biden Unleashed the Greatest Border Crisis in U.S. History (Posthill Press/Bombardier Books) and also America’s Covert Border War: The Untold Story of the Nation’s Battle to Prevent Jihadist Infiltration (Posthill Press/Bombardier Books, February 2021). The two-time National Press Club award winner, a former journalist of 23 years, currently serves as the Texas-based Senior National Security Fellow for the Center for Immigration Studies (CIS), a Washington, D.C. policy institute for which he writes reporting-based opinion editorials, speaks, and grants media interviews about the nexus between immigration and national security. He frequently reports from the southern border, traveling widely inside Mexico, Central America, and South America. He has testified before Congress as an expert witness and regularly appears on radio and television outlets to discuss illegal immigration and border security matters.
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