PALO ALTO, Calif. -- The mother of an ex-Stanford swimmer convicted of sexually assaulting an unconscious woman begged a judge to show mercy to her son in a newly-released letter, written before his controversial sentencing to six months in jail.

"I beg of you, please don't send him to jail/prison," wrote Carleen Turner, the mother of Brock Turner, in the letter to Santa Clara County Superior Court Judge Aaron Persky. "Look at him. He won't survive it."

She said she feared her son, 20, would become a "major target" in jail or prison because he is required to register as a sex offender and because of the publicity the case has generated.

"Stanford boy, college kid, college athlete -- all the publicity -- this would be a death sentence for him," his mother wrote. "Having lost everything he ever worked for his entire life and knowing the registry is a requirement for the rest of his life certainly is more than harsh."

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After his March conviction on three felony counts for the 2015 sexual assault, Turner was sentenced to six months in jail and three years of probation, but could be released in as little as three months. The maximum possible sentence for the charges he was convicted of is 14 years in prison; prosecutors sought six years behind bars.

Santa Clara County Superior Court Judge Aaron Persky's sentence -- which follows a recommendation from probation officials -- has led to widespread outcry and a campaign to recall him. One juror who convicted the former swimmer has called the sentence "ridiculously lenient," though some commentators have defended the sentence.

A handful of students demonstrated to protest the sentence at Stanford's graduation Sunday.

Carleen Turner's letter written in support of her son -- along with a slew of other letters addressed to Persky vouching for Brock Turner's good character -- surfaced Friday as a part of a release of the Turner case file by the County of Santa Clara Superior Court.

The woman said the guilty verdict "destroyed" her family and that her son is a "shattered and broken shell of the person he used to be" and "utterly terrified and traumatized." She also rejects the portrayal of her son as wealthy and entitled, telling the judge she and her husband are "a working middle-class couple with Midwestern values."

"Brock told us what happened and his accounting of the events that night never changed from the first time he told us everything," the woman wrote. "He was a shy and awkward 19-year-old, far away from home trying to fit in with swimmers he idolized. He is the most trustworthy and honest person I know. He was telling the truth. We knew once we had the opportunity to tell what happened this would all go away."

Brock Turner and his family have come under fire in recent weeks for public statements they've made about the case, including the ex-swimmer's statement to probation officials in which he blames his behavior on alcohol and the "college lifestyle." In another controversial statement, Turner's father said his son is paying a "steep price" for "20 minutes of action out of his 20 plus years of life."

In a victim impact statement that has since gone viral, the young woman that Turner assaulted called on him to take responsibility for his actions, saying, "assault is not an accident."

"You have been convicted of violating me with malicious intent, and all you can admit to is consuming alcohol," the woman wrote. "Do not talk about the sad way your life was upturned because alcohol made you do bad things. Figure out how to take responsibility for your own conduct."