In a news conference on Wednesday morning, Montgomery County District Attorney Risa Vetri Ferman announced the arrest of 30-year-old Michael Henry of the 900 block of N. 41st Street in Philadelphia.
Henry is accused of being a straw purchaser, someone who buys guns for others who are not allowed to.
In this case, investigators say Henry bought a total of nine guns for Andrew Thomas, the man who shot and killed Officer Fox before killing himself back in September.
Police say Henry bought a total of nine guns - seven handguns and two rifles - and all were given to Thomas. The purchases happened between April and July.
"Of particular note, the Beretta used to kill Officer Fox was purchased on May 30th, just one week after Mr. Thomas was placed on probation in Montgomery County for forgery," Ferman said.
According to Ferman, Henry and Thomas met in April and, shortly thereafter, Henry started buying firearms for a payment of $500 at stores in Montgomery and Chester counties.
After the purchase, the gun would be handed over in the parking lot of the store, Ferman said.
In the arrest warrant, Henry quotes Thomas as saying that he "wasn't ever going back to jail," he "wouldn't go alive," and that he would "shoot a cop." Henry has a history of drug addiction, Ferman said.
The gun used to kill Officer Fox is in police possession. Eight other guns, however, are still on the street and authorities are worried they will find their way into the wrong hands.
Henry is charged with nine felonies, each relating to the illegal sale of firearms and giving sworn falsification to authorities. He faces more than 60 years in prison.
Officer Fox lost his life in an ambush on September 13th.
Police say Fox was looking for Thomas, who drove down the wrong lane past an accident scene in a stolen SUV. Investigators say Thomas ambushed Fox, firing four shots from a hidden elevated position along the Schuylkill River Trail.
Investigators say Thomas then turned the gun on himself.
While Thomas had only one prior arrest for a minor theft, he had been the prime suspect in the disappearance of his fiancee, Maria Procopio, in 1999.
As the investigation continues, Ferman released a list of aliases used by Thomas. She released those names in the hopes that someone will recognize one of them and come forward with more information.
Those names are:
Ronald W. Blackshear
Robert P. Diggans
Eric T. Piggans
Jeremiah G. Hough
David F. Bracken
Alan Weston Clark
George C. Dyer
John S. Francis
Joseph R. O'Conner
Ronald A. Woodland
Henry, meanwhile, remains in Montgomery County Prison. His bail has been set at $1-million.