Colorado lawyers specializing in drunken-driving cases are questioning the validity of thousands of convictions after a technician who certified the state’s breath-test machines said his signature was forged on more than 100 records in 2013.

In addition, a former laboratory director’s signature is still being used on some certificates more than a year after she left the Colorado Department of Public Health and Environment in July 2015. Those certificates are being used in DUI trials to prove machines were recording accurate blood-alcohol content.

“This is the lab we’re asking to go into court and testify to the veracity of their machines,” said Darren Cantor, president of the Colorado Criminal Defense Bar. “It really makes me question whether the CDPHE is capable of doing that.”

Gov. John Hickenlooper has rejected a call from the defense bar for an independent investigation into the certification process used for every breath test machine in the state. In an e-mail to The Denver Post this week, the governor’s legal counsel said a thorough review already has been done, and no evidence of misconduct was found.

“We believe that an independent investigation is not needed at this time, but if new facts emerge, we can always reconsider,” said Jacki Cooper-Melmed, the governor’s chief legal counsel.

The certifications are important to DUI suspects and their attorneys because prosecutors, judges and juries rely heavily on the results of alcohol breath tests when weighing verdicts and punishments. Under state law, no expert is required to testify about a breath-test machine’s accuracy so the certificates are the sole proof used in a trial to show that a machine is working properly.

“These are the machines prosecutors are using to convict people in court,” said Sarah Schielke of the Life and Liberty Law Office. “They say they are scientific and reliable.”

The Colorado Department of Public Health and Environment validates, certifies and maintains the Intoxilyzer 9000, which is used to test the blood-alcohol content of every suspected drunken driver in Colorado. There are 200 machines in use at 165 law enforcement agencies across the state.

Mike Barnhill, a former electronics specialist in the state lab, said he raised concerns about the machines’ certifications after a supervisor told three people — who were not technicians and two of whom were not state employees — to calibrate and validate the machines and then sign his name on the certification forms.

While the governor’s office and the state health department said an internal investigation had been conducted, Barnhill questioned how deep investigators could have looked when they never spoke to him.

“I can’t believe they conducted a complete investigation when no one called and said, ‘Hey, Mike, you’re making these allegations. Let’s talk,'” Barnhill said.

The defense attorneys said the breath machines should have been calibrated and validated by trained technicians, and the certifications should have been signed by the person who conducted the tests.

In a rush in 2013 to deploy the machines to police and sheriffs, the state health department’s lab brought in a lawyer and a marketing specialist from the Intoxilyzer 9000’s manufacturer and a department intern to validate and certify them, Barnhill said.

Barnhill and another technician set up about two dozen of the 165 machines sent to each law enforcement agency in the state, he said. But the man who ran the breath alcohol-testing program, Jeff Groff, told everyone to enter Barnhill’s passcode to operate the machines and then to sign his name to the certifications, Barnhill said.

Barnhill said he objected to Groff’s orders but was overruled. Barnhill quit in 2015.

Schielke said she and other attorneys have counted 130 apparently forged certificates.

Questions first were raised about the machines’ certifications after DUI defense lawyers began noticing breath-machine certifications being used in court cases in late 2015 with the signature of former state health department laboratory director Laura Gillim-Ross on them even though Gillim-Ross no longer worked at the agency, Schielke said.

Gillim-Ross said in an affidavit that her duties did not include certification of instruments or signing certificates and that she did not authorize anyone to use her electronic signature. Gillim-Ross also said she has been served subpoenas to testify about her signature in several DUI cases, according to a copy of the affidavit provided to The Post.

Schielke provided a copy of a certificate, valid from Nov. 22, 2016, through Nov. 22, 2017, that shows Gillim-Ross’ signature on it.

Mark Salley, a state health department spokesman, said Gillim-Ross’ signature is no longer being used and has been removed from all but five or six devices.

The Gillim-Ross discovery led defense attorneys to start digging into the Intoxilyzer 9000’s rollout in 2013, and they learned of Barnhill’s allegations of forgery, Schielke said.

Since the Intoxilyzer 9000s went into service, Schielke and other lawyers have sent Colorado Open Records Act requests to the health department’s lab asking for data that show how a particular machine was validated, she said. Those requests have been denied.

“When we say, ‘Can we see the validation data to see if these are scientific and reliable,’ they say say, ‘No, those have been destroyed,’ ” Schielke said. “But they say here are the validation certificates, which we’ve learned have been forged.”

In a statement, Larry Wolk, the state health department director, said the department learned about Barnhill’s allegations last fall. The department conducted an internal investigation to determine whether unqualified people had certified the Intoxilyzer 9000s, but he said officials concluded that an appropriate process had been used.

The health department’s public information office also said calibrations and verifications were conducted by the appropriate personnel or under their supervision. Those results were reviewed twice before the machines were deployed. The machines are revalidated and recertified every year, the health department said.

But Schielke said those are the certificates with the former lab director’s name on them. Schielke is challenging the Intoxilyzer 9000 in a federal lawsuit against the Louisville Police Department, the state health department and its employees, and CMI, the company that makes the machine.

She also said lawyers representing clients in Weld County were able to get 33 DUI cases dismissed after they were able to show an Intoxilyzer 9000 was recording blood-alcohol levels higher than they actually were. The machine’s calibrations were off, she said.

Lawyers now are working to get other cases dismissed.

“It’s just so fundamentally unfair to everyone involved,” Schielke said. “Anyone who has done a breath test since these machines were implemented could be in jeopardy and they should be scrutinized is what we’re finding out.”