Samir Ahmad, 29, of Philadelphia, was taken into custody on October 19 by federal agents.
Court documents say two of the firearms Ahmad sold on Oct. 13 were traced by law enforcement as being used in a deadly ambush shooting after a football scrimmage at Roxborough High School two weeks earlier.
The Sept. 27 shooting killed 14-year-old Nicolas Elizalde of Havertown, Pa. and left four other teenagers wounded.
SEE ALSO: Suspect wanted in deadly shooting near Roxborough High School turns self in
Officials said Ahmad was employed with the Philadelphia Sheriff's Office beginning in Feb. 2018. He was terminated on Oct. 19 and is in custody.
The FBI said the case began back on April 27.
One of their informants was able to purchase a revolver from Ahmad. The transaction was allegedly recorded on an audio device.
According to court documents, the same informant met again with Ahmad on Oct. 13. The FBI said Ahmad sold him the two semi-automatic pistols used in the Roxborough shooting and ammunition.
SEE ALSO: School officials respond after deadly ambush shooting near Roxborough High School
During the exchange, the informant said that he was "illegal" and would "get deported" if he was caught in possession of a BB gun.
Officials said Ahmad replied, "You don't got to worry about none of that."
Images were provided from a video recording device planted on the informant.
We also see Ahmad receiving payment for the transaction as well. Ahmad made $3,000 from the sale of the firearms, according to investigators.
Then five days later, on Oct. 18, court documents said the two met a third time.
Officials said Ahmad was recorded selling another gun and also two ounces of the drug crystal methamphetamine.
If convicted, Ahmad could face a maximum penalty of 15 years in prison.
Action News spoke with former FBI Agent Brad Garrett on putting together a case like this.
"It's very tough to get out of a charge where you're in video with a gun, with drugs and a conversation about selling them," said Garrett.
Garrett said putting these cases together isn't easy and now he's interested to know what Ahmad might admit to.
"Through plea negotiations, he may say, 'I'll give you person A, B and C. I'll give you a pipeline of where I get guns,'" said Garrett.
Garrett said methods used to trace the two guns back to the Roxborough shooting are hard to dispute.
"That type of forensic evidence is really pretty solid. My guess is it'll likely hold up in court," said Garrett.