Lawyer Michalis Zafeiropoulos was murdered in his office in central Athens on Thursday night.
According to authorities, two armed men entered the building on Asklipiou Street and shot Zafeiropoulos in the head and chest.
An associate of the 52-year-old lawyer, who was in the office at the time, was locked in another room by the assailants, according to initial reports.
Zafeiropoulos was a well-known criminal lawyer and the son of former New Democracy MP Nondas Zafeiropoulos. His murder prompted a reaction from Greece's political parties.
“I express my disgust at the cold-blooded murder of M(ichalis) Zafeiropoulos,” tweeted New Democracy leader Kyriakos Mitsotakis tweeted. “(He was) A good lawyer, distinguished ND member and very good friend.”