"At the request of the Santa Barbara Sheriff, I have directed the Division of Law Enforcement with the assistance of the Civil Rights Enforcement Section and Criminal Law Division to conduct an independent investigation into whether the rights of Michael Jackson were violated when he was booked and arrested earlier this month," Attorney General Bill Lockyer said in a statement.
"We will work as quickly as possible to conduct a thorough and fair investigation."
Meanwhile, California law enforcement officers denied Wednesday that Jackson was abused during his arrest for child molestation.
Santa Barbara County Sheriff Jim Anderson said Jackson was treated properly while in his department's custody and denied that anything improper had been done, Fox News reported.
He played a videotape showing Jackson appearing well, rather than in any obvious pain.
Jackson, 45, is charged with performing lewd or lascivious acts on a child under 14 and two counts of administering an intoxicating agent, reportedly wine. The singer is free on $3 million bail and has maintained his innocence.