Alan Krueger, a groundbreaking Princeton University economist who served as a top adviser in two Democratic administrations, died over the weekend, according to a statement from the university. He was 58.

The cause of death was suicide, Krueger's family said in a statement released by Princeton.

“It is with tremendous sadness we share that Professor Alan B. Krueger, beloved husband, father, son, brother, and Princeton professor of economics took his own life over the weekend," the family said. "The family requests the time and space to grieve and remember him."

Krueger was an expert on the labor market and, in particular, the impact of a minimum wage. His research concluded that a higher minimum wage did not generally slow hiring as many conservative critics have argued.

After serving as a Labor Department economist under President Bill Clinton, Krueger worked for President Barack Obama as a top Treasury official and then as chairman of the Council of Economic Advisers from 2011 to 2013.

"Over the weekend, America lost a brilliant economist, and many of us lost a dear friend," Obama said in statement Monday in which he warmly remembered his former colleague.

"Alan was someone who was deeper than numbers on a screen and charts on a page. He saw economic policy not as a matter of abstract theories, but as a way to make people’s lives better," Obama said, adding that, "through it all, he had a perpetual smile and a gentle spirit — even when he was correcting you."

"That’s what made him Alan — a fundamentally good and decent man," Obama said.

Krueger had been teaching at Princeton since 1987. His research extended to such issues as economic inequality and the consequences of opioid addiction for the job market.

He also applied his economic work to some unconventional areas. Krueger found, for example, a surging wealth gap within pop music, illustrating in a 2005 paper how an increasing share of concert revenue was flowing to a narrow top sliver of recording artists.

While serving under Obama, he developed and popularized the concept of the "Great Gatsby Curve." It showed that high economic inequality corresponds with low economic mobility on a generation-to-generation basis. In short, it meant that when economic disparities between the rich and everyone else are wide, people's ability to improve their financial health depends even more heavily on their parents' economic status.

The curve was named after F. Scott Fitzgerald's iconic literary character Jay Gatsby, who rose from being a poor Midwestern boy to a wealthy bootlegger.

But Krueger was perhaps best-known for his research on the minimum wage with David Card. Their 1993 paper found that a rise in New Jersey's minimum wage had had no effect on employment in the state's fast-food sector compared with the same sector just across the state line in Pennsylvania.

Admired in both economic and political circles, Krueger was known as an avid tennis player and for frequently taking time to discuss the nuances of public policy with reporters.

Gene Sperling, who worked with Krueger in the Obama administration as the director of the National Economic Council, tweeted: "Just shocked, just stunned, so, so saddened."

"Alan has been my friend and colleague for over 20 years — and one of the very most consequential economists of our generation," Sperling said. "His pathbreaking work on minimum wage was only one of many ways he used his genius for the good of all."

If you or a loved one are looking for help, please call the National Suicide Prevention hotline at 1-800-273-8255.