Action News has learned that one detective reportedly attended the rally in support of President Donald Trump that preceded the insurrection Wednesday.
A mob of pro-Trump supporters stormed the US Capitol, vandalizing and assaulting officers. Five people died including a Capitol police officer. Benjamin Phillips of Ringtown, Pennsylvania also died after suffering an apparent medical emergency.
SEE ALSO: Alleged Trump supporters charged include man seen with Pelosi's lectern, horned QAnon promoter, WV lawmaker
Sources tell Action News that the detective works in the recruitment division and is tasked with screening new recruits to make sure they are fit to serve. Part of the detective's job involves screening the social media accounts of those recruits.
Authorities are working to determine if any other police department personnel were in attendance during the rally. The name of the detective under investigation is not being released.
Philadelphia police released a statement on the investigation Sunday night saying, "We are aware of social media posts that allege that a Philadelphia Police Department detective may have been in attendance at the events on Washington, DC on January 6th. An IAB investigation has been opened to determine if any PPD policies were violated by the detective, and if they participated in any illegal activities while in attendance. The Detective's assignment has been changed pending the outcome of the investigation."
SEE ALSO: 'It cost her her life': Trump supporter who died from apparent trampling in US Capitol riots followed QAnon, family says
Police Union President John McNesby says the detective denies any wrongdoing.
"It's cut and dry. she was there, she didn't do anything according to her, and we move on to the next issue," said McNesby. "You're an officer, you're sworn, you're supposed to act like that on-duty and off-duty. She went somewhere on her day off and that's her First Amendment right, to legally gather or do whatever they intended to do."
Now we're learning this probe is not the only city investigation being launched into behavior at the Capitol last Wednesday.
"This is not just a police issue. We are looking a few other potentials, in a couple other departments and we'll see what the extent of their activity there was. Hopefully it's just their First Amendment," said Mayor Jim Kenney, who declined to list the other departments launching investigations.
Across the country, police and fire departments are opening probes into officers who attended the rally. In Seattle, Western Pennsylvania and Texas, officers are under investigation to determine if they took part in the violence.
Dozens of people have been arrested in connection with the protest and riot, including 12 people from Pennsylvania and one South Jersey man.