The 18-year-old who allegedly responded to London Eley's offer has also been arrested, the Philadelphia Daily News reported Tuesday.
Police Lt. John Walker of Southwest Detectives said Eley, 20, posted an offer May 23 of a "stack" -- slang for $1,000 -- to kill Corey Jerome White. She was allegedly angry after a fight with White.
When Tim Bynum of Upper Darby responded, he and Eley discussed the project and she then sent him a description of White and his address, Walker said. A relative of White spotted the exchange and notified police.
Bynum was charged Friday with violations of gun laws after a loaded .22-caliber gun was found in his home. He was charged with attempted murder in Philadelphia the next day.