A 20-year-old registered Maryland sex offender pleaded guilty Friday in Calvert County Circuit Court to the October 2003 rape and murder of a 14-year-old relative who lived near him in Calvert County, the Calvert County State's Attorney's Office said.

Edward L. Frostbutter of Chesapeake Beach withdrew his plea that he was not criminally responsible and entered a guilty plea through his public defender, Sheila Sullivan, said Deputy Calvert County State's Attorney Laura Martin.

Appearing before Calvert County Circuit Court Judge Marjorie L. Clagett, Frostbutter pleaded guilty to first-degree murder and first-degree rape in the killing of Cindy Storms on Oct. 19, 2003, in Chesapeake Beach. Frostbutter could face a maximum sentence of life in prison without the possibility of parole when he is sentenced Feb. 11, Martin said.

According to a police affidavit outlining the crimes, Frostbutter had been infatuated with the girl and became angry when his feelings were not reciprocated.

Frostbutter, then 19, told investigators during an interrogation last year that he entered the home where Storms lived to talk with her after a family gathering there. During their encounter, Frostbutter became angry and choked and raped her, according to the affidavit.

Storms, whose step-grandmother is a sister of Frostbutter's father, was found dead in her bedroom the next morning.

Frostbutter, who pleaded guilty to the November 2001 molestation of an 8-year-old boy, served 16 months before being released from jail in April 2003. In this case, he had been held without bond on charges of murder, rape and burglary.

Storms, who was a freshman at Calvert High School, lived with her grandfather William Nelson and step-grandmother Toni Nelson in the same neighborhood where Frostbutter lived with his parents.

Frostbutter told police that he first became angry with Storms during a casual get-together of the Nelson and Frostbutter families at the Nelson home on Oct. 19, 2003, according to court documents.

Frostbutter told police that he was mad at Storms because she "treated him differently from other family members," police said in the affidavit filed with the court.

After dinner, Frostbutter went outside the Nelson home to sit on a porch swing, and relatives later told police that he "appeared to be bothered or upset by something," according to the affidavit.

He then left the porch and was seen speeding away in his car. Frostbutter told police that before midnight, he returned to the Nelson home, entered through an unlocked back door and confronted Storms in her bedroom, according to the affidavit.

Frostbutter told investigators that he choked Storms and stuffed a sock in her mouth to stifle her screams, causing her to lose consciousness, the affidavit states. He said he then tied her hands behind her back and raped her, police said.

Just after midnight, Frostbutter called his sister's boyfriend and told him to tell the family goodbye for him. Then he drove to Pennsylvania.

He called his family by cell phone the next day, after Storms's body had been discovered, according to the affidavit.

Using cellular call records and the global positioning system in Frostbutter's phone, police located him just outside of Harrisburg, Pa., and arrested him there.

Frostbutter had been charged in two other sex crimes. In 2002, he pleaded guilty in the 2001 child molestation case. He was charged with raping a girl in a restroom at Calvert High School in January 2002, but the charges were dropped when the victim declined to cooperate with authorities, according to prosecutors.

In the Calvert High School rape case, Frostbutter told authorities he suffered from multiple personality disorder and had an alter ego named Sam, according to court records.

Edward Frostbutter, 20, could face a maximum sentence of life in prison without parole. An Arundel Middle School yearbook photo of Cindy Storms, who was found dead in her Calvert bedroom.