HOUSTON -

An email from the Department of Public safety has warned district attorneys about errors in drug evidence analysis.  Evidence that wasn't properly tested could have resulted in faulty convictions since 2006, officials said.

In the email released on Friday, the DPS said all cases with evidence tested by one particular forensic scientist at the Houston Regional Lab in northwest Houston, Jonathan Salvador, are being reviewed. He has been suspended from casework pending an internal investigation.

Prosecutors in 30 counties have been notified about the issue.  The lab handles cases for Harris County as well Fort Bend, Galveston, Brazoria and Matagorda counties.

DPS officials said the technician conducted nearly 5,000 tests.

Montgomery County's D.A. said he will review as many as 3,000 cases because of the new development. 

The Harris County D.A.'s Office said about 300 cases, most of which are closed, may be affected and will all be reviewed.

"We have a list of all cases that have been disposed of and that are currents, and we're asking that every single one of those be retested," Harris County District Attorney Pat Lykos said.

If retesting shows any drug evidence that led to a conviction is questionable, that will likely mean the defendant will get a new trial.

"If there is a question about the validity of evidence, then we want to to everything possible to ensure its integrity," Lykos said.

Veteran defense attorney Dan Cogdell said this raises questions about other cases the lab has handled.

"Apparently this guy's mistakes flew under the radar for three or four years, and they're just now discovering his mistakes," Cogdell said. "What about other mistakes that they haven't discovered?"

He said that any defendant convicted on results from the lab has a basis for appeal.

"It's a lot like saying, 'We discovered one of our eyewitnesses was blind and he's been blind for some time,'" Cogdell said. "That's going to raise questions about other eyewitnesses in their other cases."

District attorneys offices in all the affected counties are looking to see if any evidence in their criminal cases had been handled by the suspended lab technician. 

DPS officials have not said if the errors were accidental or intentional.

Salvador has been employed by the DPS since 2005.

The Houston Regional Crime Lab is one of 13 DPS crime labs operating across Texas.  It received its DPS accreditation in December 2007, which will last until this December.  The lab runs tests on controlled substances, toxicology, firearms' tool marks, DNA and trace evidence.