The FBI is investigating whether the suspect in Saturday's shooting rampage in which a congresswoman was critically wounded was the same person who posted a rambling Internet manifesto accusing the government of mind control and demanding a new currency.

Jared Lee Loughner, 22, of Tucson, was taken into custody moments after the shooting at a political meeting held by Democratic Representative Gabrielle Giffords in a supermarket parking lot. At least five people died and Giffords was left fighting for her life with a head wound.

In a series of YouTube videos, a person identifying himself Jared Lee Loughner complains about government mind control, treasonous laws, illiterate dreamers and the U.S. currency.

The government is implying mind control and brainwash on the people by controlling grammar, the person wrote in one of the videos, which contain only music and white text on a black background.

No! I won't pay debt with a currency that's not backed by gold and silver. No, I won't trust in God.

The postings describe no coherent political ideology, said Mark Potok, an investigator with the Southern Poverty Law Center, which tracks violent extremists. Loughner was not in the Center's database of hate groups and radicals.

He certainly sounds like he's gone off the deep end, but at the same time, he is mouthing some rhetoric that is quite reminiscent of the anti-government movement ... It's hard to know what to make of his ideology.

A federal law enforcement official said the FBI was trying to establish whether the shooting suspect was the same person who posted the videos.

In a biographical sketch on the site, Loughner writes that he attended Tucson-area schools and says his favorite books include Adolf Hitler's Mein Kampf, Karl Marx's Communist Manifesto, and Ken Kesey's One Flew Over the Cuckoo's Nest, set in an insane asylum.

My favorite activity is conscience dreaming: the greatest inspiration in my political business information, the writer of the post says.

(Reporting by Andy Sullivan, Roberta Rampton and Jim Vicini; Editing by Paul Simao and David Storey)