Hennepin County attorney investigates credentials of influential forensic expert

The chief technology officer of a nationally respected computer forensics company in Minnesota is under investigation by the Hennepin County Attorney’s Office for allegations he has lied about his education and employment history.

Mark Lanterman, who owns Computer Forensic Services in Minneapolis, has contributed to hundreds of criminal and civil investigations in state and federal court over the last three decades — including expert witness testimony, affidavits and declarations.

The disclosure that the Attorney’s Office was investigating Lanterman was filed by Managing Attorney Michael Radmer as part of Brady/Giglio review, a term for how prosecutors must disclose to the defense any information about a case that would benefit the person charged with a crime or any question about the credibility of a potential witness.

Allegations that he lied about his biographical history first surfaced from Wisconsin attorney and forensic investigator Sean Harrington, who has an updating document about Lanterman’s career and education on his website.

In a video statement, Lanterman said, “I am deeply disappointed that the Hennepin County Attorney’s Office issued a notice regarding my employment and education history without first contacting me.

“This letter marks the first occasion I have been informed about any concerns related to my employment history and the notice itself lacks any specific details or explanation.”

In a filing to U.S. Magistrate Judge Cathy Waldor in New Jersey this month regarding allegations about his background, Lanterman said Harrington has essentially been conducting a smear campaign against him by sending these allegations to “news outlets, prosecutors, law enforcement, Courts and court staff, professional associations, and others across the country.”

In a statement, the Attorney’s Office said it does not contract with Lanterman but is working to identify any cases that might be affected because of Lanterman’s work with law enforcement — so far they have discovered nine such cases but Radmer said in his disclosure that more are anticipated.

The disclosure also noted that a Wisconsin lawyer had brought concerns around Lanterman’s background to the county.

In an interview Friday, Harrington said the Attorney’s Office did not reach out to him about Lanterman but said he has provided documentation at the request of investigators.

Lanterman is well respected in Minnesota legal circles. He served six years on the Lawyers Professional Responsibility Board before his term ended in 2024. He is an adjunct law professor at the University of St. Thomas and served on the U.S. Secret Service Electronic Crimes Taskforce and is certified with the Department of Homeland Security. He has been quoted numerous times in the Minnesota Star Tribune as a computer forensics expert and was hired by the St. Paul Pioneer Press to search the Star Tribune’s computers in a lawsuit over confidential advertising information in 2007.

His firm was also responsible for extracting cellphone footage Winston Smith recorded while being shot in Uptown in 2021 after the Minnesota Bureau of Criminal Apprehension insisted no such footage existed after having possession of Smith’s phone for two years.

Documents from Hennepin County Board meetings show that Lanterman’s company has been awarded upward of $1.5 million to provide “digital forensic services” to the Hennepin County Sheriff’s Office since 2018. That includes an active contract not to exceed $850,000 approved in 2022 for services through 2025.

The Hennepin County Sheriff’s Office said it was aware of the investigation by the Attorney’s Office. “We are evaluating our contract and we have no comment at this time,” it said.

Lanterman has long maintained in his résumé and court filings that he graduated from Upsala College and conducted postgraduate studies at Harvard. Harrington alleges that is untrue, and says several public comments Lanterman has made about cases he has worked on and his past employment are also untrue.

Harrington said there is nothing vindictive about his examination of Lanterman’s background — and it has nothing to do with being in the same line of work.

“My interest in doing this is not a selfish one, I cannot emphasize that enough,” Harrington said. “If he went out of business tomorrow, I’m not going to get anything out of it, nothing, zero.”

In the court filing in New Jersey, Lanterman says he contacted Felician University — which maintains Upsala records after Upsala went bankrupt in 1995 — and was told his diploma and transcripts could not be found and it “might be possibly due to unresolved money-related issues.” He also told the court that he completed a four-month certificate program in cybersecurity at Harvard in 2018.

The disclosure from Radmer states that so far the Attorney’s Office has been unable to verify Lanterman’s “educational and employment background and the office will not rely on his work or testimony in pending cases.”

Chief Hennepin County Public Defender Mike Berger said his office is reviewing any cases where Lanterman may have been involved.