Man arrested 12 years after reportedly assaulting his step-daughter, resulting in her death

SAGAMIHARA, Japan (NBC) - Tokyo Metropolitan Police arrested a 42-year-old man on Thursday for abusing his 11-month-old step-daughter to death 12 years ago.

Shinsuke Hotta is charged with assaulting Al Sakurai in his Tokyo apartment in 2006.

Hotta's step-daughter died two months later.

Police suspected from the beginning the suspect had likely assaulted Al. But the investigation hit a snag because Hotta insisted the baby girl had fallen from a Kotatsu, a traditional Japanese table with a heater.

Findings from the latest studies on child abuse this year, however, led investigators to conclude that Hotta's explanation does not match the injuries.

Hotta admitted to the charges, saying he wants to atone for his crime.