Joe Mahr

Joe Mahr is an investigative reporter who has written about topics ranging from government corruption and court mismanagement to lax policing efforts and questionable lottery tactics. An Ohio University graduate, Mahr joined the Tribune in 2009. He was on a team that won a Pulitzer Prize in 2004 and on another that was a finalist in 2015.

Cook County sheriff’s police officers patrol the 95th Street Red Line CTA station in Chicago on March 11, 2026. (Chris Sweda/Chicago Tribune)

CTA riders and workers have been assaulted at rates at least double other public transit agencies

March 25, 2026 at 4:34 p.m.

Workers and passengers on the Chicago Transit Authority have been assaulted at rates at least double those of comparable public transit systems around the country, according to a Tribune analysis...

Marimar Martínez stands outside a truck service shop on Dec. 26, 2025, where she called 911 after she was shot five times in October by a Border Patrol agent in Brighton Park. Prosecutors originally claimed Martínez, as part of a convoy of protesters, rammed federal agents' vehicle near 39th Street and Kedzie Avenue and then tried to run over an agent, but felony charges were later dropped after her attorney argued agents caused the crash and needlessly shot her. (E. Jason Wambsgans/Chicago Tribune)

Rioters? Agitators? Immigration agents’ claims against US citizens mostly fall apart in court.

December 30, 2025 at 5:00 a.m.

Time and again, Donald Trump’s immigration agents claimed horrific crimes at the hands of protesters in Chicago. Those allegations of abuse did not withstand the scrutiny of judicial review.

A federal agent points his gun sideways during an immigration enforcement action in the Little Village neighborhood on Nov. 8, 2025. Longtime urban police leaders questioned that tactic and many others used by immigration agents during Operation Midway Blitz. The policing leaders said the agents routinely behaved in ways that — beyond potentially being unconstitutional — unnecessarily endangered suspects, protesters, innocent bystanders and the agents themselves. (Armando L. Sanchez/Chicago Tribune)

Immigration agents’ poor tactics in Chicago made for needless safety risks, experts say

December 7, 2025 at 9:35 a.m.

A Tribune review found immigration agents in Chicago routinely broke urban policing protocols meant to limit danger to themselves and others.

Cook County Jail booking photos of Jose Coronado Meza starting on July 3, 2024, from left, then again on Dec. 14, 2024, Jan. 5, 2025, and last on July 7, 2025, after he was accused of shoplifting twice, then arrested twice more for alleged illegal gun possession. (Cook County sheriff's office)

A border crosser. An execution killing. And political theater.

December 3, 2025 at 3:10 p.m.

Trump’s DHS blamed Democrats for a Chicago homicide, but it didn't take key action in a case exemplifying effects of political divide.

Border Patrol officers detain a man while conducting immigration enforcement actions in the Edison Park neighborhood of Chicago on Oct. 31, 2025. (Armando L. Sanchez/Chicago Tribune)

Nearly 1,900 immigrants were detained during the first half of Operation Midway Blitz. Most had no criminal record.

December 2, 2025 at 1:43 p.m.

Newly released federal data shows that immigration agents booked in roughly 1,900 immigrants in the first half of Operation Midway Blitz – two-thirds of whom had no known criminal convictions...

Megan Siegel wears a flag cape while holding the hand of her daughter, Matilda, while protesting outside the U.S. Immigration and Customs Enforcement holding facility in Broadview, Nov. 14, 2025. The Siegel family lives in Shabbona, near DeKalb. Siegel said she has been protesting outside the Broadview facility up to five times per week. (Chris Sweda/Chicago Tribune)

Sharp drop in detainees at ICE facility in Broadview follows temporary restraining order

November 18, 2025 at 6:05 p.m.

The number of detainees held at the U.S. Immigration and Customs Enforcement processing center in Broadview has dropped precipitously since a federal judge ordered the government to comply with requirements...

The 6-year-old daughter of Marina Lopez Perez is held by her 13-year-old brother and her father, Marina’s husband, as she goes down a slide on Aug. 1, 2025. Lopez Perez was detained on June 4 after she showed up to a check-in with ICE in its South Loop facility. The native from Guatemala spent three days in Broadview before she was taken to Grayson Country Detention Center in Kentucky, where she awaits her release or deportation. (Stacey Wescott/Chicago Tribune)

‘Dehumanizing’: Inside the Broadview ICE facility where immigrants sleep on cold concrete

August 3, 2025 at 11:17 a.m.

An investigation by the Chicago Tribune found that immigration detainees have been held for days at the processing center in west suburban Broadview.

Agentes federales escoltan a personas esposadas hasta camionetas blancas estacionadas frente a la oficina de ISAP, administrada por el Servicio de Inmigración y Control de Aduanas (ICE), en el South Loop, el 4 de junio de 2025. (Eileen T. Meslar/Chicago Tribune)

Los arrestos del ICE aumentan en Chicago bajo el gobierno de Trump, muchos sin condenas, según muestran los datos

July 30, 2025 at 12:45 p.m.

Con la administración Trump impulsando una aplicación de la ley de inmigración mucho más agresiva en todo el país y en Chicago, un análisis del Tribune de los datos recientemente...

People in handcuffs are escorted by federal agents to white vans parked outside the Intensive Supervision Appearance Program office run by Immigration and Customs Enforcement in the South Loop on June 4, 2025. (Eileen T. Meslar/Chicago Tribune)

ICE arrests increase across Chicago under Trump, many with no convictions, data shows

July 23, 2025 at 11:39 a.m.

A Tribune analysis reveals a sharp overall increase in the number of people booked into detention processing centers in the Chicago area in the 150 days since President Trump was...

Marles Blackman enters the Markham courthouse with an attorney on June 27 after a dinner break for the jury deliberating in her murder trial. (John J. Kim/Chicago Tribune)

Stalled Justice: Mother convicted of killing her toddler, 13 years after charges filed

July 1, 2025 at 11:36 a.m.

In the notoriously slow Cook County court system, a jury has convicted a south suburban woman of murder in the 2011 death of her son.

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