The prosecution of five Blackwater employees over the notorious 2007 Nisoor Square massacre hit a snag Wednesday, when lawyers for one of the five accused federal prosecutors of "misconduct" in the case.

In a court filing Wednesday, lawyers for Nicholas Slatten, a Tennessee native who served two tours of duty in Iraq before joining Blackwater, alleged "a disturbing case of prosecutorial misconduct, undermining the integrity of the judicial process," the Associated Press reports.

The defense team said prosecutors had little evidence against Slatten and kept vital information from the grand jury that evaluated the basis for the criminal charges against him.

All five defendants had been charged with manslaughter. They had also been charged under an anti-machine-gun statute that would see them receive 30-year sentences under federal law.

The Justice Department last week asked the court to drop the charges against Slatten, but asked to reserve the right to file new charges against him at a later date. Slatten's lawyers argued Wednesday against that right, and also asked for a public hearing into the matter. The case has so far been heard behind closed doors, and the Justice Department's reasons for dropping the charges against Slatten have not been made public.

The defense allegations complicate a case that many human-rights activists have been watching closely. The September, 2007, massacre in Nisoor Square left 17 people dead and is widely considered to have been a turning point in the Iraq war, as public sentiment in the US and Iraq began to tilt away from the use of for-profit security firms in war zones.

Earlier this month, the New York Times reported that Blackwater "authorized payments of about $1 million" to Iraqi officials, in an attempt to bribe them into allowing the security contractor to continue operating in Iraq.

Blackwater has since renamed itself Xe Services. An investigative report in The Nation, published Monday, alleges that Xe is operating in Pakistan, where it is running targeted assassinations of militants and may be involved in a covert bombing campaign of Taliban and Al Qaeda positions in the country.

The US government adamantly denies the allegations, which would suggest deep US involvement in Pakistan's war against terrorist insurgents. The article's author, Jeremy Scahill, alleged earlier this week that the Pentagon attempted to "intimidate" him into not running the story.