ORLANDO, Fla. — The parents of a black teenager who was fatally shot by a neighborhood watch volunteer asked federal officials Monday to expand their investigation to look at the prosecutor who recused himself in the case.

Trayvon Martin’s parents allege in a letter sent to the U.S. Department of Justice that State Attorney Norm Wolfinger met with the Sanford police chief within hours of the teen’s death and that together they overruled a detective’s recommendation that the shooter, George Zimmerman, be charged with manslaughter. The letter claims a lead investigator filed an affidavit stating that he didn’t find Zimmerman’s story credible.

The prosecutor, Norm Wolfinger, called the allegations “lies” and said no meeting took place.

“I’m outraged by the outright lies contained in the letter,” Wolfinger said in a statement. “I encourage the Justice Department to investigate and document that no such meeting or communication occurred.”

Wolfinger recused himself from the case two weeks ago and a special prosecutor from Jacksonville is now investigating the shooting. Wolfinger said he wanted to avoid the appearance of a conflict of interest and to tone down the rhetoric in the case.

Martin’s parents want to know why Wolfinger’s office made the decision not to charge George Zimmerman after the Feb. 26 shooting. Zimmerman told police he was attacked and fired in self-defense. The U.S. Justice Department is already looking into the Sanford Police Department’s handling of the case.

Separately, Florida Sen. Gary Siplin asked the special prosecutor, Angela Corey, to select members of a grand jury from outside Sanford, if she chooses to send the case to a grand jury. Corey has the option of presenting the case before a grand jury, filing charges without a grand jury’s assitance or not charging Zimmerman.

A spokeswoman for Corey has said there is no guarantee the case will be sent to a grand jury, even though Wolfinger had scheduled a grand jury to hear the case on April 10.