ST. PAUL  (AP) -- A St. Paul man has admitted shaking his infant son so hard he caused the baby permanent brain damage.

Thirty-three-year-old Jeffrey Allen Davis pleaded guilty Tuesday in Ramsey County Court to malicious punishment of a child.

Davis says the shaking lasted 10 to 15 seconds, and that the boy's head moved "back and forth" several times.

After the shaking last March, Davis told police his 6-week-old son's head moved "like a bobble-head doll." Davis said he was frustrated by his son's screaming.

Prosecutor Juan Hoyos says the boy suffered permanent brain injury, including damage to his eyesight.

Sentencing is set for Feb. 25.

(Copyright 2011 by The Associated Press.  All Rights Reserved.)

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