A former parking lot manager at the Smithsonian National Air and Space Museum annex in Chantilly has pleaded guilty to his involvement in a conspiracy to steal more than $1 million in visitors' parking fees, court records show.

Abeselom Hailemariam, 33, of Alexandria, pleaded guilty Friday to a charge of conspiracy to commit theft of public money. He is scheduled to be sentenced on July 19 in federal court in Alexandria and faces a maximum penalty of five years in prison.

From about March 2009 through summer 2012, Hailemariam was the location manager at the 2,000-vehicle parking lot at the Steven F. Udvar-Hazy Center. The center is a Smithsonian facility that houses the Space Shuttle Discovery, a Concorde and other aircraft.

Hailemariam was responsible for supervising parking-booth attendants, accounting for revenue that was brought in from visitors' parking fees, and creating accurate reports about the parking lot's revenue and operations, according to court documents.

Prosecutors said that over a period of about three years, parking-booth attendants at the lot would keep visitors' parking fees and conceal the thefts by failing to hand out serialized parking tickets to visitors and by unplugging the electronic vehicle counters in the booths. At the end of their shifts, the attendants would submit reports to Hailemariam that undercounted the number of vehicles that had entered the parking lot.

Hailemariam reviewed and accepted the attendants' reports that he knew contained falsified numbers. He then prepared reports using the inaccurate numbers that were provided to the parking management company that employed him and the Smithsonian, according to court documents.

The attendants also paid Hailemariam a share of the stolen revenues after their shifts ended. And Hailemariam instructed the attendants to stop stealing parking fees at times when the conspirators thought they were at a higher risk of being detected, court documents stated.

The group stole almost $1.4 million worth of parking fees, prosecutors said.

Two former parking-booth attendees who were part of the conspiracy have already pleaded guilty to their roles in the thefts. Meseret Terefe, 37, was sentenced to 20 months in prison, and Freweyni Mebrahtu, 46, was sentenced to 27 months in prison, prosecutors said.