A 22-year-old man pleaded guilty Tuesday to stabbing his former girlfriend to death last October in a high-profile stalking-murder case in Mitaka, west Tokyo.

Charles Thomas Ikenaga was charged with murder for fatally stabbing high school student Saaya Suzuki, 18. Ikenaga reportedly began stalking Suzuki after she rejected his pleas to resume their relationship.

As the trial opened at the Tachikawa branch of the Tokyo District Court, Ikenaga appeared to have difficulty concentrating and kept turning around to look at the gallery and often licked his lips.