Trey Eric Sesler, 22, of Waller, was charged Wednesday with murder in the deaths of his mother, father and brother, the Houston Chronicle reported.
Police found the bodies of Lawton Ray Sesler Jr., 58, his wife, Rhonda Wyse Sesler, 57, and their son, Mark Alan Sesler, 26, shot to death in their home Tuesday.
While searching the home, police found no murder weapon, but remorseful messages were written on the walls, said Michael Williams, a crime scene investigator and detective with the Waller Police Department.
"He basically said it in the first person, stuff like, 'I love my family,'" Williams said.
Trey Sesler was taken into custody Tuesday night after a day-long manhunt.
The 22-year-old told investigators he and at least one other former Waller High School student were also planning a Columbine-style shooting at the high school, said a law enforcement official who asked to not be named.
Sesler was apparently obsessed with the 1999 shooting, during which two seniors went on a shooting spree, killing 12 classmates and one teacher before committing suicide at Columbine High School in Colorado, the official said.
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Beyonce flaunts bikini body, Blue Ivy in vacation pics