WASHINGTON (CNN) -- A U.S. Army Criminal Investigations Division investigator has recommended changing the official manner of death for a soldier electrocuted while showering at his base in Iraq from "accidental" to "negligent homicide," according to an e-mail from the investigator obtained by CNN.

Ryan Maseth, a 24-year-old Green Beret, died in a shower at his base in Iraq on January 2, 2008.

The investigator blames KBR, the largest U.S. contractor in Iraq, and two KBR supervisors for the incident, saying there is "credible information ... they failed to ensure that work was being done by qualified electricians and plumbers, and to inspect the work that was being conducted."

The e-mail, written late last year, says the investigation report was being reviewed by CID headquarters for a legal opinion to determine probable cause before the case could be referred to the military court system or the Department of Justice for possible action. No charges have been filed.

Sgt. Ryan Maseth's manner of death has not officially been changed, CID spokesman Christopher Grey told CNN.

"It may change, but not at this time," he said, adding that the Armed Forces Institute of Pathology would make that determination.

KBR spokeswoman Heather Browne told CNN the company "cannot comment on the report by an unidentified Army investigator because we have not seen the report."

"KBR's investigation has produced no evidence that KBR was responsible for Sgt. Maseth's death," Browne said. "We have cooperated fully with all government agencies investigating this matter and will do so in the future."

CNN first reported the death of Maseth, a highly decorated, 24-year-old Green Beret, last spring. His January 2, 2008, death was just one of many fatalities now believed to be linked to shoddy electrical work at U.S. bases managed by U.S. contractors, according to Pentagon sources.

The Pentagon's Defense Contract Management Agency last year gave KBR a "Level III Corrective Action Request" -- issued only when a contractor is found in "serious non-compliance" and just one step below the possibility of suspending or terminating a contract, Pentagon officials said.

In KBR's case, it means the contractor's inspections and efforts to ensure electrical safety for troops have been unacceptable and must be significantly improved, Pentagon sources told CNN.

The CID investigator's e-mail says work orders to address problems resulted in "fixes [that] were only temporary and not done to ensure no future problems would arise."

The Pentagon and its contract agency have declined requests for an interview to answer questions about Maseth's death or the other cases.

Just after Maseth's electrocution, Pentagon officials estimated that about a dozen troops had been electrocuted in Iraq. But Pentagon officials now say at least 18 troops have been electrocuted since 2003 -- many due to faulty wiring and improper grounding.

The number could be higher if deaths from Afghanistan are included, said congressional sources.

KBR's contract in Iraq is vast and encompasses numerous responsibilities including the upkeep of U.S. bases and providing basic services on the bases. The 18 electrocutions occurred in different places and under different circumstances.

At least two lawsuits have been filed against KBR, including one by Maseth's family, and investigators are trying to determine precisely what role, if any, KBR played in the circumstances that led to those deaths.

All About Iraq • The Pentagon