The West Wing actor is awaiting trial after pleading not guilty to four counts of criminal sexual contact of a minor, but his legal team have alleged "prosecutorial misconduct" and have filed a motion requesting the grand jury indictment in New Mexico be thrown out.
His lawyer Larry Stein told People magazine in a statement: "Timothy Busfield is innocent.
"This motion describes egregious prosecutorial misconduct during grand jury proceedings, thereby preventing the jurors from hearing testimony, witnesses and evidence even after repeated requests by the grand jury itself.
"The government repressed and suppressed exculpatory evidence, misstated the law and failed in the most basic due process afforded any person under either constitutional or state laws designed to protect actual innocence from abuse of government power."
The lawyer previously admitted the "indictment was not unexpected", but insisted the case was "fundamentally unsound".
Bernalillo County District Attorney Sam Bregman previously announced the indictment and said in a statement: "As with all criminal proceedings, Mr Busfield is presumed innocent unless and until proven guilty in a court of law. This case will proceed through the judicial process and is expected to move forward to trial."
The 69-year-old actor - who is married to Melissa Gilbert and has three children from previous marriages - turned himself in and was booked by authorities on January 13, just four days after the Albuquerque Police Department issued a warrant for his arrest.
The warrant came after it was alleged that he engaged in unlawful sexual conduct with 11-year-old twin boys.
On January 20, the Field of Dreams actor was released with conditions while awaiting trial.
Busfield has denied all the charges, saying in a video obtained by TMZ: "I did not do anything. They're all lies and I did not do anything to those little boys and I'm gonna fight it. I'm gonna fight it with a great team, and I'm gonna be exonerated, I know I am, because this is all so wrong and all lies."
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