By . Daily Mail Reporter . PUBLISHED: . 13:41 EST, 6 June 2012 . | . UPDATED: . 08:27 EST, 7 June 2012 . A 15-year-old boy today pleaded guilty to shooting his older sister three times in the head as she slept. Colton Harvey was charged as an adult for killing his 16-year-old sibling Candace Harvey on January 15 this year at their rural home. Harvey offered the guilty plea in exchange for being charged with second-degree murder and was handed down a 45-year prison term in Arkansas. Scroll down for video . Prom night: Candace Harvey was shot in the head as she lay sleeping by her 15-year-old brother at their home in Ozark, Arkansas . Jailed: Colton Harvey, 15, wept in court today as he was tried as an adult for the murder of his 16-year-old sister Candace. He has never explained why he shot her . The teenage boy has given no motive as to why he murdered his sister. According to 5 News the parents told investigators the two teenagers never fought. Prosecutor David Gibbons said: 'No signs that would alert somebody that this would happen, no quarrels, no fussing and fighting.' The boy cried as he addressed the . judge, at one point raising his cuffed hands to his face so he could . dab his eyes with a tissue. The scrawny, blonde teenager appeared in court with his feet shackled as he told Judge William Pearson he used a rifle to kill his sister. The judge asked: 'You stated that you murdered your sister. Is that correct?' Harvey whispered: 'Yes, sir.' Tragedy: Miss Harvey, 16, was murdered in her bed by her brother Colton, 15 . Youth: Numerous tributes have appeared online to the fun-loving teenager who appeared to have been killed by her younger brother without motive . Pearson sentenced Harvey to 30 years for second-degree murder plus 15 more because he used a gun. Prosecutors initially charged Harvey with first-degree murder which has a maximum penalty of life in prison. He could be up for parole in 12 years, depending on good behavior. 'How far did you get in school?' the judge asked the teenager, who responded in such a quiet voice that the judge had to repeat some of his answers. He responded: 'Ninth grade.' Authorities believe that Harvey killed . his 16-year-old sister after their parents left to go grocery shopping . 40 miles away. His mother Erica Harvey sobbed in court today as her son . was sentenced. Sporty: Candace was a keen basketball player and was on the Lady Hillbillies team . Guilty: Harvey offered the guilty plea in exchange for being charged with second-degree murder and was handed down a 45-year prison term in Arkansas . The sheriff said the boy seemed remorseful and had tears in his eyes when he turned himself in on January 15. Investigators found the girl's body in her bedroom at the family's home near Ozark, a town of around 3,600 people, 120 miles northwest of Little Rock. The question of why Harvey shot his . sister remained unanswered. Prosecutor David Gibbons said: 'He never did . give what I would consider to be a clear motive.' Harvey's . attorney, Bill James, said there was a history of mental illness in the . family. However an expert wasn't able to give a diagnosis because of . Colton's young age. Spirited: The 16-year-old schoolgirl shows off her cowboy boots and prom dress in Ozark, Arkansas . Innocence: Candace Harvey's mother sobbed in court today as she watched her son sentenced to 45 years for her murder . Mr James added: 'Every time I've ever seen him, he's cried. And it's not, ''Woe is me.'' It's about what he's done to his mom and what he's done to his family.' Local sheriff Anthony Boen said at the time of Harvey's arrest that deputies had never been called to the home and there weren't any reports of trouble with the teenagers. A neighbor described the family as 'nice and quiet' and the boy as a 'nice young boy'. Donna Sheppard, who lives next to the family's home, said her grandson knew the boy from school. She said: 'It's the most shocking thing I could have ever imagined.' Mrs Sheppard said she did not hear any gunshots before she left for Sunday school a little after 9am and learned about the shooting when she came home from church that afternoon. Candace Brooke Harvey was a student at Ozark High School and a keen basketball player with the Lady Hillbillies.
Colton Harvey wept in court as he admitted killing sister Candace with a rifle at rural Arkansas home . Pleaded guilty to second-degree murder and could be eligible for parole in 12 years . Siblings 'never fought', parents said . No clear motive although family had a history of mental illness .