This photo, provided by the Seoul Metropolitan Police Agency, shows the identity and mug shot of the suspect behind the murder of a woman and her daughter at an office in Seoul's Gangnam district, June 4. Yonhap

A Seoul court on Friday sentenced a man to life in prison for murdering his ex-girlfriend and her daughter over a breakup.

Park Hak-sun, 65, was indicted with physical detention on charges of stabbing his former girlfriend and her daughter, in their 60s and 30s, to death at an office in Seoul's southern district of Gangnam on May 30, after the woman told him she wanted to break up.

Park reportedly committed the crime while holding a grudge against her family for opposing their relationship.

"The defendant carried out the crime so swiftly that it seems impossible to think other than he was set on killing the victim beforehand," the Seoul Central District Court said, adding the specific crime method is "excessively cruel" to be deemed accidental.

However, the court dismissed the prosecution's demand for a death penalty, citing the lack of special circumstances to make such a punishment rightful.

Park has claimed during the hearings that he did not premeditate the crime and that it was "accidental," but these claims were dismissed by the court. (Yonhap)