A masked gunman fatally shot a UC Berkeley business professor while he visited his kids in Greece, according to several media reports.

Przemysław “Przemek” Jeziorski, an associate marketing professor at the university’s Haas School of Business, reportedly died while visiting his children in Athens, according to a Friday report from Cal’s student newspaper, The Daily Californian.

A gunman reportedly shot the 43-year-old Polish professor five times on July 4 at close range in the suburb of Agia Paraskevi near Athens, the Polish news organization TVP World reported on Tuesday. Jeziorski reportedly died near his Greek ex-wife’s house, TVP reported.

Jeziorski had two children and was locked in a custody battle with his ex-wife, according to the Polish news site.

He held a Ph.D. in economics from the Stanford Graduate School of Business and master’s degrees in mathematics and economics from the University of Arizona. He also held a bachelor’s of arts in economics from the Warsaw School of Economics.

He also previously worked as an assistant professor of economics at Johns Hopkins University in 2010 and 2011.

Łukasz Jeziorski, the professor’s brother, set up a WhyDonate site to field donations to pursue legal action in Greece, Poland and the United States, and to help repatriate his brother’s remains to Poland. The family has raised € 45,476 so far, with a goal of €95,000.

“Our family is heartbroken, and we are doing everything we can to ensure that justice is served,” Łukasz Jeziorski wrote on the site.