A man charged with killing a University of Pittsburgh student in her off-campus apartment is back in Pennsylvania after extradition from South Carolina.

Allegheny County spokeswoman Amie Downs confirmed Friday that 21-year-old Matthew Darby was in the county jail. Authorities allege that Darby used a claw hammer and two knives Oct. 8 to kill 20-year-old Alina Sheykhet, his ex-girlfriend, before fleeing.

He was arrested in Myrtle Beach after a witness reported him tampering with a window at a residence three days after the Pittsburgh slaying. He pleaded guilty to loitering and false information counts. Darby is also accused of assaulting a teenage girl days before the slaying.

Defense attorney David Shrager has called the charges "serious" but said his client didn't want to discuss them over the phone.