Five people have been arrested by the Greek authorities in the July 4 killing of a well-known University of California, Berkeley, professor, including his ex-wife and her current boyfriend, the police said.

The suspects made their first appearance in court on Thursday on charges of intentional homicide in the shooting of Przemyslaw Jeziorski, 43, who taught quantitative marketing at the Haas School of Business.

The police did not name any of the suspects, including Mr. Jeziorski’s ex-wife, whose lawyer, Alexandros Pasiatas, told the Greek news media that his client had no involvement in the killing. He also denied that the former spouses were having custody issues.

Mr. Pasiatas did not immediately respond to a request for comment on Thursday. Neither did Ermis Papoutsis, a lawyer for the ex-wife’s boyfriend, who told reporters in Greece that his client had “accepted responsibility” for the killing, without elaborating.

While visiting Agia Paraskevi, a northern suburb of Athens, Mr. Jeziorski, who was born in Poland and was known as Przemek, was approached by an attacker during the afternoon on July 4 and was shot in the chest and back, the Greek police said.

At the time of his death, Mr. Jeziorski was seeing his two young children and making legal arrangements for future visitation, something his ex-wife, who is Greek, had tried unsuccessfully to block him from doing, officials said.