MOUNT VERNON - Three days after a security guard in Mount Vernon was allegedly gunned down by his supervisor, residents living in the building are raising questions about the qualifications of those who protect them.

John Anderson, who has lived at the Levister Towers for almost a decade, says security guards rarely move from their protected glass booth overnight.  When they do, they only check the perimeter and stairwell. He also says guards assigned to the building are unarmed.

Early Monday morning, 47-year-old Richard Brown was stationed at the Levister Towers, until he was allegedly shot and killed by his supervisor, 32-year-old Dontan Jenkins.

Police say the two had a heated exchange while working together. Brown is said to have made comments about Jenkins' weight, and Jenkins allegedly returned during the overnight hours with a gun.

Officials say Brown had only been working for the Brooklyn-based company Nature's Finest LLC for 10 days and was still undergoing on-the-job training. It is unclear how long Jenkins was working for the company, but he did have a prior arrest record for assault, and most recently in 2013, drug possession.

A statement from Nature's Finest said that "in order to qualify for employment, a prospective security guard needs to be licensed by the state and undergo 8 hours of training before placement," and that Brown and Jenkins did undergo the training.

While the glass inside the building has been replaced since the incident, neighbors say the glass should be bulletproof to protect the guards and residents living there.

Jenkins remains at the Westchester County Jail charged with second-degree murder.