A 15-year-old central Kansas boy ordered to stand trial as an adult in the fire-related deaths of his mother and sister has pleaded not guilty to murder charges.

KWCH-TV of Hutchinson reports that Buhler High School student Sam Vonachen was arraigned Monday in Reno County on two counts of premeditated first-degree murder.

Vonachen also is charged with one count of attempted first-degree murder of his father, and of aggravated arson.

Authorities allege Vonachen used gasoline to ignite his family’s two-story Hutchinson home in September 2013, killing 11-year-old sister Audrey Vonachen and their mother, 47-year-old Karla Jo Vonachen.

Prosecutors have played investigators’ recorded interview of Samuel Vonachen. He told authorities that people are “awful” and he set the fire to send his family a message.