Shelley Rubin, wife of Jewish Defense League (JDL) leader Irv Rubin, said she wanted to see videotapes from inside the prison where her husband allegedly slashed his throat and fell 18 feet (5.4 metres).
Mr Rubin went into a coma and was put on a life support machine after surgery at a nearby medical centre.
But a JDL spokesman says he has since shown signs of brain activity and has started breathing on his own.
He was due to appear in court on Monday in relation to charges that he and another man plotted to bomb a mosque and the office of an Arab-American congressman.
Mr Rubin was reported to have suffered his injuries while he was standing in a queue of inmates waiting to be taken to court.
'Self-inflicted wounds'
JDL spokesman Brett Stone expressed surprise at the official version of events.
Rubin's controversial past
1978: Charged with soliciting murder after offering to pay anyone who killed a Nazi. Ultimately cleared.
1985: Investigated in connection with murder of Arab-American activist Alex Odeh. Case never solved.
2002: Won a ruling barring officials in a suburb from invoking Jesus Christ at public meetings
Claims to have been arrested more than 40 times
"The government account of what happened just doesn't add up," he told Reuters news agency.
"His spirits were just too good. He was looking forward to going to court. The Irv Rubin we know would not have done this."
But FBI spokeswoman Laura Bosley said interviews with witnesses suggested a suicide attempt.
"Without specifying too much... there is nothing to indicate that Mr Rubin suffered from anything other than self-inflicted wounds," she said.
'Wake-up call'
Mr Rubin and Earl Krugel, a dental hygienist, were arrested on 11 December 2001 on charges of scheming to bomb the King Fahd mosque in Culver City, a Los Angeles suburb, and the office of California congressman Darrell E Issa - the grandson of Lebanese immigrants.
The prosecution alleges that while Mr Krugel built the bombs, Mr Rubin selected targets and planned attacks to deliver what Mr Krugel called "a wake-up call" to Arabs.
The men allegedly wanted to demonstrate with their bombs that despite dwindling membership, the Jewish Defence League - founded in 1968 as an armed response to anti-Semitism in New York - was "alive in a militant way".
An FBI informant alerted authorities to the alleged plot.
If the men are convicted of the charges, which they deny, they could be sentenced to life imprisonment.