The woman who stole nearly $1 million from the Field Museum while working there for a decade used the money to buy expensive clothing, watches, handbags and to drive “one luxury car after another,” federal prosecutors say.

Caryn Benson faces sentencing April 21, more than a year after she pleaded guilty to the embezzlement. It was uncovered in April 2014 as the museum underwent restructuring and noticed missing cash from the membership department, museum officials have said. She stole the money by pocketing the cash visitors submitted to pay for memberships.

Now, federal prosecutors say Benson should spend as many as four years in prison after stealing from “one of the city’s most significant civic institutions and one of the largest natural history museums in the world.” Assistant U.S. Attorney Georgia Alexakis said the museum could have used that money “for numerous worthwhile pursuits.”

“These efforts would have benefited the millions of members of the public, Chicagoans and tourists alike, who annually visit the museum,” Alexakis wrote in a memo filed Monday. “Instead, the embezzled funds benefited only the defendant, an individual who took advantage of the museum’s trust in order to steal and conceal her crime.”

In fact, Benson claimed many of her extravagant purchases were gifts, according to FBI reports. They included a gold chain and a woman’s four-carat diamond Joe Rodeo watch, each about $1,500. She also spent nearly $1,000 on a men’s watch at Macy’s, and a combined $1,200 on a pair of men’s shoes and a handbag from Gucci.

Benson also worked her way up, starting in 2006, from a Toyota Camry to a 2010 Buick Enclave CX Wagon, a 2011 and 2013 Infiniti QX56 SUV, and a 2014 Nissan Maxima — trading vehicles in along the way. She also used an “unknown amount of cash” to buy a Jaguar in 2012, the feds say.

Benson admitted she took money from the Field Museum starting in about 2007. She told the feds she “started taking small amounts, but then she began taking more and more, to the point it eventually just got out of hand,” agents wrote.