A Yemeni passenger, who tried to force his way into the cockpit of a San Francisco-bound plane while screaming Allah Ho Akbar (Allah is great), pleaded not guilty, Friday, to a charge that he had interfered with a flight crew.

On May 8, Rageh Ahmed Mohammed Al-Murisi, an immigrant from Yemen, was subdued after attempting to break into the locked cockpit of a San Francisco-bound American Airlines.

Witnesses said Al-Murisi repeatedly yelled Allah Ho Akbar as he was wrestled down onto the floor by the flight crew and other passengers.

Al-Murisi's behavior made authorities suspect that he was related to some terrorist outfit, possibly al Qaeda and wanted to take over control of the plane and bring it down.

However, his lawyer Chris Morales says the man is innocent and isn't tied to any terrorist outfit.

Morales told the court on Friday that Al-Murisi abhorred violence and terrorism, including al Qaeda.

The lawyer said his client suffered from a mental illness and couldn't comprehend his actions.

He did not want to crash the plane. He was scared and nervous in his own mind. It all had to do with his mental health issues, Morales said.

Morales told the court that Al-Murisi was suffering from hallucinations for quite some time and have been hearing voices for two months before he boarded Flight 1561.

Investigations have revealed that Al-Murisi was a teacher in Yemen before he came to the U.S., where he worked in a convenience store in New York.

Al-Murisi was traveling to San Francisco to visit his relatives in Vallejo and he had board Flight 1561 in Chicago. Investigators said he had expressed suicidal intentions on the flight before trying to break open the cockpit door.

Magistrate Jacqueline Scott Corley set Almurisi's next appearance for June 23. if found guilty, Al-Murisi could face up to 20 years in jail.

He is currently being held without bail at the Santa Rita Jail in Dublin.