Loughner altar
© SplashA macabre 'altar' in the backyard of Tucson shooter Jared Loughner
FBI investigators delving into the warped mind of Tucson massacre suspect Jared Loughner are exploring whether he was influenced by the occult and a Right-wing conspiracy theorist.

In messages left on the internet before the shooting Loughner, 22, revealed himself to be a social outcast with paranoid, nihilistic beliefs and a fixation with grammar.

At a public meeting with Congresswoman Gabrielle Giffords three years ago he asked: "What is government if it doesn't exist?"

It left the politician baffled.

According to the Southern Poverty Law Centre, a US civil rights group, Loughner's language and beliefs appeared to resemble those of David Wynn Miller, a Milwaukee-based activist who believes that the US government uses grammar to control people's minds.

Miller, 62, a retired welder, has described himself as a plenipotentiary judge, ambassador, banker, genius and King of Hawaii, and invented his own form of grammar called "truth language", that is said to set people free of the government.

He said he was appalled by the shootings, but agreed with Loughner's pre-shooting internet statement that "the government is implying mind control and brainwash on the people by controlling grammar". Miller told the Milwaukee Journal that Loughner could have visited his website but he didn't know him and he was "obviously disturbed".

FBI agents combing through Loughner's life will also explore whether he was an enthusiast of the occult after a fake skull was found at his home, sitting in a plant pot with shrivelled oranges. There were candles next to it in what appeared to be some form of shrine.

The skull was concealed behind camouflage sheeting outside the home he shares with parents Amy and Randy in a middle-class area lined with palm trees.

Classmates and neighbours described Loughner as "creepy" and "an emotional cripple," and said he used to ask teachers questions about mind control in class.

They said he was an atheist who also believed that Nasa space shuttle missions, which have been flown by Miss Giffords' astronaut husband Mark Kelly, were faked.

Ben McGahee, 28, a professor at Pima Community College, said: "I remember going home and thinking to myself 'Is he going to bring a weapon to class?'"

Lynda Sorenson, 52, a mature student who had an algebra class with Loughner, wrote a series of emails in June suggesting he was "seriously disturbed".

She wrote: "We have a mentally unstable person in the class that scares the living crap out of me. He is one of those whose picture you see on the news, after he has come into class with an automatic weapon. I sit by the door with my purse handy."

Loughner was suspended in September after writing on the internet that the college was "unconstitutional".

He bought his gun from the Sportsman's Warehouse store in Tucson in November. Friends said he worked at Pima Animal Care Centre and "loved animals."

On Sunday one of the people who jumped on Loughner as he tried to reload on Saturday spoke to The Daily Telegraph. Patricia Maisch, 61, who grabbed his second magazine, said: "The woman next to me was shot and I was expecting to be next. Then two men knocked him over and somebody yelled 'Get the gun!' so I knelt up.

"He reached into his pocket and brought out a magazine. A third man came up and grabbed him, he dropped the magazine and I was able to pick it up and secure it. The three men were on him but his legs were flailing so I knelt on his ankles. He didn't look angry, just a dead face, nothing."

The three men were retired Army Colonel Bill Badger, 74, Joe Zimudie, 24, and Roger Sulzgeber.

Col Badger is thought to have jumped on Loughner first and was grazed by a bullet on the back of his head. "I grabbed him around the throat," the colonel said.