A parking lot manager at the Smithsonian’s air and space museum in Chantilly who helped swipe more than $1.3 million in parking fees was sentenced to three years and four months in prison Friday, authorities said.

Abeselom M. Hailemariam, 33, of Alexandria, pleaded guilty in April to a charge of conspiracy to commit theft of public money, admitting that he and others repeatedly pocketed the $15 charge that visitors paid to park at the Steven F. Udvar-Hazy Center, then sent fake revenue reports to the Smithsonian to cover up their crimes. Their scheme lasted from 2009 to 2012, though at times they stopped stealing if they felt someone was on to them, court filings show.

Two others have already been sentenced in the scheme, and another defendant committed suicide before her case was resolved, authorities have said. Smithsonian officials have said the losses were about 10 percent of the total gross parking revenue for the museum in a little more than three years.

Prosecutors asked in court filings that Hailemariam be sentenced to 31 / 2 years in prison, saying that he came to be a leader in the scheme because he was a parking lot manager.

Hailemariam assigned those he knew were pocketing money to the busiest lanes into the lot and “orchestrated” some of the cover-up steps, according to prosecutors. He and others not only submitted false revenue reports, but they also unplugged electronic vehicle counters and did not give parking ticket stubs to the center’s customers, prosecutors wrote in court filings.

Defense attorneys argued in court documents that Hailemariam, an Ethio­pian immigrant with two children, should be sentenced to three years and a month or less. They wrote that he was a “very generous, caring person with a big heart” and had accepted responsibility for his actions.