A marketing professor at the University of California, Berkeley, was "murdered in cold blood" while visiting his children in Greece, according to his family.
Przemyslaw Jeziorski, a 43-year-old associate marketing professor at UC Berkeley's Haas School of Business, was allegedly shot and killed in Athens on July 4 near the home where his two children -- Zoe and Angelo -- live, his younger brother Lukasz Jeziorski said in a statement. The children, who are 10-year-old twins, live with the victim's ex-wife, the professor's close friend Chemtai Mungo told ABC News.
His brother said there have not been any arrests in relation to the incident.
"I never thought something like this would happen to my family," Lukasz Jeziorski said in a statement.
Lukasz Jeziorski told ABC News that his brother's death "and the circumstances surrounding it are impossible to accept."
The professor was allegedly in Greece to attend a court hearing relating to an "ongoing division of property and custody battle," Mungo said. His brother told ABC News he wanted to bring his children to his hometown of Gdynia, Poland, "as he did every year," and that he had also planned a trip to Disneyland Paris.
"He fought for them until the end," his brother told ABC News.
Mungo, who had known Przemyslaw Jeziorski, or "PJ," for the past five years, said she was in touch with him while he was in Greece. She said he had arrived there with the expectation he would be able to take his children to Poland for a month, which was granted by "prior court arrangements," but when he got there, "there was a new dispute that had to be attended to in the courts."
He had been divorced from his wife for three years, and Mungo said the relationship "was not cordial."
Mungo said she believes the shooting was not accidental, given it occurred in a "good neighborhood in Athens." She also said that police shared with the victim's family that a masked gunman walked up to him and fired five shots in his chest and neck -- but Mungo said she is unsure who would do this.
"He was a gentle soul. He didn't have faults with anybody -- the only conflict we knew was the custody battle," Mungo told ABC News.
Lukasz Jeziorski said he has "secured legal representation in Greece" and that the family will do "everything we can to ensure that justice is served."
The victim's father just died on June 4, with this incident -- "another tragedy" -- occurring exactly one month later, the professor's brother said.
Przemyslaw Jeziorski, who had over 15 years of experience in research and teaching, earned the reputation as a "leading expert in quantitative marketing, industrial organization and applied microeconomics," according to his faculty profile. His research made "a contribution to a variety of markets, including mobile money in Africa, sponsored search advertising, radio broadcasting, car insurance and breast cancer prevention," his bio says.
He had "always wanted" to go to the United States and had "fulfilled" a dream of buying an apartment in San Francisco last year, his brother told ABC News.
Przemyslaw Jeziorski loved playing the guitar, sci-fi movies, traveling and was "very sociable," his brother told ABC News.
UC Berkeley Haas Dean Jennifer Chatman said in a statement that the school is "heartbroken" by the news of Przemyslaw Jeziorski's death and that he was a "beloved member of our marketing faculty and Haas community."
"While authorities are investigating what happened, our focus is on supporting our community during this difficult period. My heart goes out to Przemek's family and loved ones. We will miss him," Chatman said in a statement.
Holding back tears, Mungo told ABC News she hopes her friend is remembered for being "kind, loving and a brilliant scholar."
"Just being around PJ, there was a lot of laughter, lightness and humor. He loved his children greatly," Mungo said.
The motive behind the incident remains unclear.
Hellenic Police -- Greece's national police service -- did not immediately respond to ABC News' request for comment.