The star witness against Timothy McVeigh in the Oklahoma City bombing acknowledged under cross-examination Tuesday that his story has completely changed since the blast, and so have his looks and his speech.

"Of course I'm changing my language," Michael Fortier testified. "I'm not going to sit here and curse in front of all these people."With his hair neatly cut, his beard shaved off and his earring gone, Fortier took the stand in a pressed suit for a second day to testify under a plea bargain that McVeigh spent months planning the April 19, 1995, federal building blast that killed 168 people and injured hundreds.

McVeigh attorney Stephen Jones suggested Fortier was lying to cover his own role, saying he actually rented a storage shed to store explosives but claimed McVeigh did it.

"No sir, that's not true. Not at all," he said.

In nearly an entire day on the stand Monday, Fortier insisted he was telling the truth when he testified McVeigh cased the federal building months before the blast and even considered crashing his truck bomb through the glass front doors in a suicide attack.

Fortier said McVeigh, driven by rage over the 1993 government siege at Waco, Texas, wanted to bomb the building to "cause a general uprising in America."

Fortier said he refused to join the plot and learned of the bombing while watching television: "Right away I thought Tim did it."

Fearful he would go to prison and even be executed, Fortier said he initially lied to everybody, from the FBI and to the media, insisting McVeigh was innocent. He said he finally came clean and agreed to cooperate when he was faced with testifying before a grand jury.

Jones seized upon the changing stories when he began his cross-examination Monday, suggesting Fortier was slanting his testimony against McVeigh to secure a lenient sentence recommendation from prosecutors.

Fortier pleaded guilty to four federal charges, including failure to report the bombing plot and lying to the FBI. He faces up to 23 years in prison but likely will get less because of his testimony.

McVeigh, 29, could get the death penalty if convicted.