By Daniel Trotta

A Virginia mother was sentenced to 21 months in prison on Wednesday after her 6-year-old son shot his school teacher with a gun that she had bought illegally.

The first-grade teacher, Abigail Zwerner, survived the wound from a 9mm semiautomatic pistol and was hailed as a hero for evacuating students from her classroom after she was shot at a Richneck Elementary School in Newport News last January.

Even in a nation regularly rocked by gun violence, the case was especially jarring given the boy's age and the setting.

The investigation quickly shifted to how the boy obtained the handgun, leading to federal charges against his mother, Deja Nicole Taylor, 26. In June she pleaded guilty to possessing a firearm while using a controlled substance and making a false statement while purchasing a gun.

She was also prosecuted in Virginia state court, pleading guilty to a charge of felony child neglect. She is due to be sentenced in that case on Dec. 15.

Defense attorneys had pleaded for leniency and a maximum of six months in prison for Taylor, saying in a court filing that she was "deeply saddened, extremely despondent and completely remorseful" over the shooting and had trouble with addiction and mental health issues that "will only be exacerbated by imprisonment."

But the sentence of 21 months matched exactly what prosecutors sought, which was in the middle of the federal sentencing guidelines of 18 to 24 months, according to another court filing.

U.S. District Court Judge Mark Davis told the sentencing hearing that "this case cries out for imprisonment," according to The Virginian-Pilot, given Taylor's previous run-ins with the law for gun- and drug-related incidents.

"There were too many opportunities, too many off-ramps. This was not a one-off," Davis said.

Taylor wiped away tears as the judge passed sentence, the Washington Post reported.

According to police, the boy had taken the handgun from home, placed it in his backpack and removed it while Zwerner, 25, was teaching class, firing a single shot through her hand and into her chest.

Zwerner endured five hand surgeries to treat the gunshot wound and still has the bullet in her chest, The Virginian-Pilot reported.

Zwerner's lawyer, who filed a $40 million lawsuit against school administrators on her client's behalf, has said that Richneck Elementary officials had been warned three times the day of the shooting that the boy was armed.

(Reporting by Daniel Trotta; Editing by Michael Perry)