The commander of the Douglas County crime scene investigations unit faces county and federal charges tied to allegations of evidence tampering in a double-murder case.

David Kofoed was charged Wednesday in Cass County Court with one count of evidence tampering. On Thursday U.S. Attorney Joe Stecher announced federal charges.

U.S. Attorney Joe Stecher says in a news release that the 52-year-old Kofoed has been charged in a four-count federal indictment. That includes two counts of deprivation of rights under the color of law.

He is accused of planting a speck of blood collected from the car of one of two men initially charged in the 2006 murders of Wayne and Sharmon Stock of rural Murdock. Authorities had said the blood belonged to Wayne Stock.

Matthew Sampson and Nicholas Livers were initially charged but eventually cleared. Two Wisconsin teenagers have since been convicted and sentenced.

Lawyers for Sampson and Livers say that blood was planted by officials in a car to implicate the men.

Kofoed maintains his innocence.

Livers and Sampson, have filed lawsuits that accuse law enforcement of trying to cover up a botched investigation.

Kofoed had been placed on paid leave after the lawsuit was filed. But he returned to work in July 2008 after passing a polygraph test about how he handled evidence in the case.

Charges of evidence tampering against Kofoed could lead defense attorneys to re-examine convictions in the Omaha area.

Jerry Soucie with the Nebraska Commission on Public Advocacy says he has been in touch with several prosecutors concerning criminal cases on which Kofoed has worked.

Kofoed has been handling crime cases in the Omaha area for years.

Kofoed has been commander of the CSI unit since 2000, and worked as a crime lab specialist for the Omaha Police Department from 1990 to 2000.

Among the cases for which Kofoed has handled evidence is the murder case against Ivan Henk, who was sentenced in 2005 to life in prison for killing his 4-year-old son, Brendan Gonzalez, whose body has never been found.

Kofoed also testified in the murder trial of Christopher Edwards, who was sentenced in 2007 to 80 years-to-life in prison for the death of a 19-year-old college student Jessica O'Grady. Her body has never been found either.