Ashley Howes loves kids and she was excited about her first real babysitting job. But what happened that led the 13-year-old to be charged with second-degree murder for the death of 19-month-old Freya Garden.  Correspondent Harold Dow reports for 48 HOURS MYSTERY: "Blaming the Babysitter," to be broadcast Saturday, Feb. 4 (10:00-11:00 PM, ET/PT) on the CBS Television Network.

It was very unusual for Ashley Howes' father, John, to let his youngest child spend a long weekend in Seattle, acting as a mother's helper for family acquaintance Morningstar Garden. It was the Martin Luther King, Jr. holiday weekend in 2005, when Ashley watched Madeline, 5, and Freya. Ashley's father and stepmother were to attend a party Saturday night with Morningstar and her boyfriend, Gracian Cline.

Ashley's 16-year-old stepsister was supposed to be in charge of all the children, including Ashley, with the kids staying at a motel that night. But plans changed, and instead they ended up at a house owned by Cline. Ashley's older sister never made it.

Ashley claims that Morningstar and Cline spent most of Saturday behind a closed bedroom door before leaving for the party that evening. By Sunday, Ashley says she began to feel overwhelmed by her duties. That same afternoon, Ashley and Madeline went to the movies, while Freya stayed with her mother and Cline for two hours. Later, while Ashley gave Freya a bath, Morningstar called the teen's parents to say Ashley was doing a great job, and asked if she could stay one more night. Ashley's father reluctantly agreed.

Sometime during the next hour, Morningstar and Cline left the house to run an errand. While they were out, Ashley says she heard a thud from the room where Freya was sleeping. When she went to check Freya, Ashley says she found the toddler in a fetal position groaning. She called 9-1-1, and an ambulance rushed Freya to the hospital.

Doctors told police it looked as if the toddler had been violently shaken: she had major head injuries, including a blood clot in her brain. Police briefly questioned Freya's mother and her boyfriend, but they questioned Ashley for hours, without a lawyer or her parents present. At around 3:00 AM, detectives decided to videotape Ashley's statements. Police also gave Ashley a doll to help her show them what happened. Two hours later, Freya was pronounced dead and Ashley was charged with second-degree murder. During the investigation, police found drugs in the room where Freya's mother and boyfriend were staying. Police say there was no proof that the drugs were theirs -- no drug charges were filed.

Ashley denies she did anything to hurt Freya. But, before a trial could begin, her lawyer, Brian Hershman, would ask the court to throw out all of his client's videotaped statements to police. Hershman argues detectives did not properly conduct their interviews and that Ashley did not willingly tell her story to police. He says the tapes reveal a young, innocent girl who was manipulated and badgered by investigators for hours, without her parents or an attorney present.

Hershman also claims there was rush to judgment. He says detectives never thoroughly investigated Freya's mother, Morningstar, and her boyfriend, Cline. Cline refused a 48 HOURS interview. Police say they thoroughly investigated the two, and are adamant the couple is innocent.

Will the videotapes of Ashley be admitted into evidence? And will anyone ultimately be held criminally responsible for the death of Freya?

48 HOURS MYSTERY: "Blaming the Babysitter" is produced by Mary Noonan, Ian Paisley and Lourdes Aguiar. The senior producer is Anthony Batson and the executive producer is Susan Zirinsky.