HOUSTON (AP) – Evidence from 8,000 criminal cases has been mislabeled and improperly stored in the Houston Police Department’s property room, police said Thursday.

The evidence, much of it from murder investigations, is in 280 boxes and dates from 1979 to 1991, police said. An evidence box should contain material from only one case under department rules.

Police Chief Harold Hurtt said it will take about a year for the department to finish going over the evidence. He blamed the situation on “poor work habits” and “sloppy efforts” by crime lab personnel.

Hurtt said investigators found that Jim Bolding, former head of the department’s DNA lab, was responsible for improperly documenting about 900 submissions, some of which dealt with evidence found in the 280 boxes.

Investigators are evaluating whether any of the 8,000 cases involve DNA evidence in 379 cases that are part of an ongoing review of the crime lab.

The lab’s DNA section has been closed since a December 2002 audit revealed that analysts lacked training, cases were not sufficiently documented and evidence may have been exposed to contaminants.

Since March 2003, the Harris County district attorney’s office has been reviewing evidence processed by the DNA lab and has ordered retests in the 379 cases.

The first retest returned found no DNA evidence to link a Houston man to a 1998 rape case in which he was sentenced to 25 years in prison. He was freed after 4½ years and received a pardon.