Police have been able to thwart a terrifying plot by a deranged St. Louis teenager to kidnap his friend's 10-year-old sister in the middle of the night, then allegedly smother her to death and rape her dead body, authorities say. John Thomas Classen, 17, is now in custody after breaking into his classmate's home in O'Fallon around 12.40am Thursday, using a window he deliberately left unlocked two days earlier, and hiding in the basement for over four hours. He then went up to the main level of the house, where the young girl - who he was reportedly in love with - was asleep on the couch, put his hand over her mouth and threatened to kill her if she screamed. Classen then allegedly dragged her to the basement, but the two slipped and fell down the stairs. Scroll down for video . Deranged: John Thomas Classen, 17, of O'Fallon, Missouri, was 'in love' with his friend’s 10-year-old sister and kidnapped the girl early Thursday, planning to smother and 'rape her dead body', then flee town, police said . Classen allegedly took his victim out the window he used to get into the house - located in the 100 block of McCluer Drive - and then to his car, which was parked in a nearby street. The girl continued resisting. He drove off, headed for a wooded area next to an apartment complex. 'He wanted to talk to her about the first time they met,' the victim's 18-year-old brother, who asked not to be named, told The St. Louis Post-Dispatch. 'My sister told him she was hurt and wanted to go back home.' Meanwhile, back at the house, the family's three dogs started barking at the sound of Classen and the victim tumbling down the stairs. The mother woke up, now about 5.25am, and started screaming after realizing her daughter was missing. She looked outside and allegedly saw Classen dragging her little girl down the street and quickly called 911. Scene: Classen allegedly broke into this O'Fallon home around 12.40am Thursday, using a window he left open while visiting the house two days earlier. He hid in the basement for four hours before kidnapping the victim . Police established road road blocks using a one-mile radius and we able to stop Classen at a checkpoint near the entrance to the Prairie Village subdivision, off the South Outer Road of Highway 364. The girl was rescued, shaken and with minor injuries. Police found a list on Classen's cellphone that detailed his plans. 'Take her to a secondary location, explain everything to her, smother her, rape her dead body, clean up and then pose the body … photograph her, dispose of her body, leave town,' police documents stated. 'We were very, very fortunate to get on it right away,' O'Fallon Police Chief Roy Joachimstaler said. The victim's brother goes to school with Classen at Fort Zumwalt West High School. They have known each other for about five years. The brother said he first realized something was amiss last summer, when Classen sent his sister a message on social media. It said he thought she was a cute and that he loved her. 'I took it in the best possible way and thought he was just being friendly,' he brother said. Safe: The 10-year-old victim is seen here being attended to by ambulance officers following Classen's arrest . Injured: The girl had a sore ankle from the fall down the stairs and scratches on her back, but was fine . Arrest: Quick-thinking police were able to intercept Classen within 35 minutes of him snatching the girl . The cellphone Classen wrote said that he was going to rehearse the abduction and wear latex gloves. After pulling off the alleged rape and murder, he planned to flee town and hide in a foreclosed home, and surviving by stealing cars and money. Part of the note read: 'She will die as she lived, my only friend. The darkness has engulfed everything … I’ll miss you.' Classen has been charged with child kidnapping, burglary and two counts of child abuse. 'This is one of those things that makes no sense; there’s no logical reason behind it,' the brother told STLtoday. 'I hope he gets punished and that he gets some mental help.' Classen's bail was set at $1.5 million.
John Thomas Classen, 17, broke into friend's home at 12.40am Thursday . He used a window he left unlocked two days earlier . Hid in basement for four hours before snatching sister, 10, who he 'loves'
Victim's mom woke up and called police . Cops were able to stop Classen at a checkpoint and rescue the girl . Police say he planned to smother her and rape her dead body .