By Brad Segall

NORRISTOWN, Pa. (CBS) — Authorities in Montgomery County, Pa. say the gun that was used to kill Plymouth Township police officer Brad Fox last month was purchased legally but then illegally put into the hands of the killer.

Michael Henry of Philadelphia is now facing nine felony charges for the illegal “straw” purchase of nine firearms between April and July.

Prosecutors say the 30-year-old man legally bought seven pistols and two rifles from stores in Montgomery and Chester counties, but then sold them to Andrew Thomas for $500 each.

Thomas used a nine-millimeter Beretta pistol to kill Fox last month before turning the gun on himself. (see related stories).

“He put nine guns into the hands of a felon, and one of those guns was used to kill a police officer,” says Montgomery County DA Risa Ferman, “and we will go to court and we will ask our courts to do justice.”

Court documents reveal Henry told police that Thomas told him that if he was stopped by police, he wasn’t going back to jail and he would “shoot a cop.”

Bail for Henry has been set at $1 million cash. Henry’s next court appearance is scheduled for next Tuesday.

Authorities are still looking for the remaining eight guns, and they are hoping someone will come forward with information that will lead them to the remaining firearms.