RAPID CITY, S.D. (AP) — A California man who authorities say was arrested in South Dakota with his mother's body found in the vehicle he was driving is fighting extradition.

Tosten Walsh Lommen, 30, appeared in court in Rapid City on Friday and declined to waive extradition to California, KEVN-TV reported. A hearing on the matter is scheduled for Feb. 20.

Authorities allege Lommen killed his mother, Michelle Walsh, 58, sometime around Dec. 30 while the two were living in her home in Palm Springs, California.

Lommen was arrested on New Year's Day on suspicion of drunk driving and eluding police following a 50-mile (80-kilometer) chase on Interstate 90 in South Dakota that reached speeds surpassing 100 mph. Authorities said they found his mother's body wrapped in a blanket in the back of his sport utility vehicle, and that an autopsy concluded Walsh had died from head and neck injuries.

He was charged with murder in California's Riverside County on Jan. 8.

Lommen had been scheduled to enter pleas Wednesday to South Dakota state charges of felony aggravated eluding and misdemeanor drunken driving, reckless driving and resisting arrest. Assistant Attorney General Scott Roetzel dropped those charges early in the week, and the hearing was canceled.

"We dismissed our file so (Lommen) could go back to (California)," attorney general spokeswoman Sara Rabern told the Capital Journal . "The much more serious charges he is facing (are) out west."

Lommen remains jailed in Rapid City in lieu of $2.5 million bond.