The FBI and U.S. Justice Department have been reviewing the circumstances around since 2019, the federal agencies said Tuesday in a joint statement.
The review is focused on determining whether a federal civil rights investigation is warranted, the statement said.
"The matter is ongoing, and we are in the process of gathering additional evidence from the Aurora Police Department and other parties," it said. "To date, the City of Aurora has been cooperating."
McClain's family attorney expressed surprise at the decision.
"I am both surprised and pleased to hear that a civil rights investigation is being considered by the FBI, U.S. Attorney's Office, and the Department of Justice's Civil Rights Division," Mari Newman said in a statement.
"The Aurora Police Department has a long and sordid history of both brutality and racism, and a comprehensive civil rights investigation is long overdue. I invite these agencies to reach out and will happily provide information to assist in this critically important investigation," Newman's statement said.
McClain, a 23-year-old Black man was stopped by three White officers in August as he walked home from a nearby convenience store. A 911 caller had described a "suspicious person," according to a police overview of the incident.
After McClain resisted officer contact, a struggle ensued and an officer placed McClain in a carotid hold -- or chokehold -- and he briefly lost consciousness, according to an overview of the incident police provided.
McClain began struggling again once he was released from the hold, the report said. When paramedics arrived, they administered the drug ketamine to sedate McClain, the report said. McClain suffered a heart attack while in the ambulance and was declared brain dead three days later, the district attorney said in a letter.
The three officers involved have been reassigned to "nonenforcement" duties, authorities last week.
The officers' safety was a primary reason for the move as various police and city employees have received complaints and threats recently, a spokeswoman for the Aurora Police Department
More officers on leave after photos surface
Multiple Aurora officers were also placed on administrative leave after images surfaced of them near the site where McClain died.
An investigation is pending, the chief said in a statement.
"This investigation will be publicly released in its entirety promptly upon its conclusion," chief Vanessa Wilson said. "This will include reports, photographic evidence obtained, officer's names, and my final determination which can rise to the level of termination."
In a statement posted on Twitter, Aurora Mayor Mike Coffman said he was "deeply troubled" by facts surrounding the photographs, which were shared with him by the chief.
"I understand that there are due process procedural requirements that are in progress. I will comment on the case once the #investigation is complete," Coffman
In their statement, the FBI and Justice Department said they were aware of "recent media reports" around the investigation into a photograph.
"We are gathering further information about that incident to determine whether a federal civil rights investigation is warranted," their statement said. "We will have no further comment until both of those reviews are completed."
