An attorney for a Weirton teen who is accused of making threats against a school said investigators are hindering his client's defense case.

Mark Mentzer, 19, is accused of threatening the commit a terrorist act. He and two other Weir High School students were arrested after a school resource officer said the students were connected to threatening text messages that were circulating around the school.

Charges against Mentzer include threatening to commit a terrorist act. During the course of the initial investigation, police confiscated a number of items from Mentzer and his home, including a suicide note and what they claim were bomb-making materials.

In court Monday, Mentzer's attorney, Fred Risovich, said police and FBI agents are discouraging witnesses involved in the case from cooperating with an independent defense investigator.

Risovich said, if that's true, it would likely go against FBI and state policy. He also said such practices deprive Mentzer of his due process.

"Based on the private investigator that I have out in the field, that the FBI agent and or the city police officers are advising witnesses not to talk to the defendant's investigator," Risovich told the judge.

Risovich also submitted a letter to Hancock County Magistrate Court outlining an agreement with Prosecutor Jim Davis to share statements and push a preliminary hearing back. The hearing was rescheduled until March 22.

Neither Risovich nor Davis commented after the hearing.

Federal authorities are still investigating and collecting statements from those involved in the case. Mentzer remains free under the same conditions of this previous bond. If he is indicted by a grand jury, it won't likely be until April.

Stay with NEWS9 and WTOV9.com for continuing coverage.

Previous Stories: October 2, 2009: Student Accused Of Terroristic School Plot Released From Jail October 2, 2009: Students Accused In School Plot Appear In Court September 29, 2009: Social Worker Analyzes School Threat Suspect's Note September 25, 2009: 3rd Student Arrested; Police Increase Presence At Weir High School September 24, 2009: 2nd Student Arrested After Police Find Bomb-Making Materials