Israel Mireles filed an appeal on June 11 with Mexican authorities who had granted the U.S. extradition request.
Mireles is charged with capital murder, rape and aggravated criminal sodomy in Sander's death.
Sander, who was an 18-year-old student at Butler Community College, was last seen alive leaving a bar in El Dorado, Kan., with Mireles on Nov. 23, 2007. Sander's body was found on Nov. 29 about 50 miles east of El Dorado.
Authorities tracked Mireles down on Dec. 19 at a relative's home in Melchor Muzquiz, Mexico. He has been held pending extradition.
A higher court in Mexico will hear Mireles' appeal, a process that could take another three to four months.