Lefcourt said he doubts media appearances or even a book deal could recoup the millions of dollars he said the family has likely spent.
"But who knows? If there's a book deal and it's a best seller? Who knows?" he said.
Bill Ponall, president of the Central Florida Association of Criminal Defense Lawyers, said people often invest "large sums of money" on behalf of family members in murder cases "because they are essentially fighting to save the defendant's life."
Italy does not permit the death penalty, but one of the possible verdicts for Knox was a life prison sentence.
"The sentence the defendant faces is usually a life sentence or some term of years which would require them to serve most of their life in prison. For that reason, people are often willing to take money out of retirement accounts or go into debt to help a family member in this situation."