Experts give conflicted testimony on Vossen's competency

Algene Vossen, 79, is charged with second-degree murder in the 1974 killing of Mabel "Mae" Agnes Boyer Herman in Willmar. A competency hearing was held Sept. 10, where multiple doctors gave conflicting reports after a competency evaluation declared him unable to assist in his defense.

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WILLMAR — A competency hearing was held for Algene Vossen on Friday in a Kandiyohi County District Courtroom to determine his ability to stand trial for a 1974 Willmar homicide. Multiple evaluators gave conflicting reports on Vossen's mental state.

Competency evaluations are considered confidential and are not normally available to the public.

Algene Leeland Vossen Photo via Minnehaha County (S.D.) Jail

Vossen, 79, is charged with second-degree murder in the 1974 killing of Mabel "Mae" Agnes Boyer Herman in Willmar. He was charged last year after a Willmar Police Department cold case team was able to connect Vossen to the homicide after matching his DNA with a sweater Herman was wearing the night she was killed.

A Willmar native, Vossen was living in Sioux Falls, South Dakota, when he was arrested in July 2020. He was booked into the Kandiyohi County Jail in September following extradition proceedings and made his first appearance in Kandiyohi County Court on Sept. 4, 2020. He was held on $1 million bail.


Vossen was released from jail in October of 2020. He was hospitalized in St. Cloud from Oct. 17 to Oct. 27 for medical treatment. He was then released into the care of his niece in Iowa, where he currently remains.

Evaluators disagree on Vossen's mental state

Dr. Harlan James Gilbertson, called by the Kandiyohi County Attorney's office, said in court that Vossen is competent to stand trial and criticized reports from both the court-appointed evaluator, Dr. Tricia Aiken, and the defense evaluator, Dr. Sara Vaccarella, who both testified against Vossen's competency.

Aiken, who works in private practice and is often called to testify for both defense counsels and prosecutors, testified that Vossen needs additional testing and that she believes Vossen has a neurocognitive disorder. Gilbertson's examination determined Vossen has "anti-social personality disorder with psychopathic traits or features with age-related decline," but not a neurocognitive disorder. Vaccarella's report aligns with Aiken's conclusion that Vossen is not fit to stand trial due to neurocognitive decline.

None of the evaluators are neuropsychologists.

No ruling was issued by the presiding judge, Minnesota Eighth Judicial District Judge Stephen Wentzell, with written briefs by Vossen defense attorney Kent D. Marshall, of Barrett, and Assistant Kandiyohi County Attorney Kristen Pierce due by Oct. 15.

"There is no evidence of cognitive impairment," Gilbertson said in court. He also called into question why Vossen was given multiple written tests by Vaccarella despite Vossen having tremors that would negatively affect his test scores. Vossen's tremors "would artificially suppress" his scores, according to Gilbertson, who said he did not administer them to Vossen.

"I did not rely on that test to inform my opinions, but I had to include the data because I did the tests," Vacceralla testified in court.

Gilbertson, a licensed psychologist who has a private practice in Mora, testified that, while Vossen's overall scores showed him in the low-average range, this was not enough to show impairment to stand trial or the potential need for civil commitment. His scores also align with the same type of tests Vossen took in 1976.


Gilbertson said he reviewed almost a thousand pages of records, including police reports and medical records, and spent about 2 1/2 hours with Vossen in August.

Gilbertson cited Vossen's understanding of court proceedings and the roles of those in court, legal terms such as making a plea or the difference between a jury trial or a bench trial, and Vossen's ability to communicate with his lawyer.

"He knew that if was found guilty he'd face life in prison," Gilbertson said in court. Gilbertson also acknowledged Vossen's memory issues, but said these can be solved by providing prompts. Vaccarella and Aiken also testified that Vossen would often need prompts to remember words or events.

Aiken testified Friday that in her first interview with Vossen, he seemed unable to concentrate and that his desire to plead not guilty didn't make sense as he didn't have a defense strategy in mind. Vaccarella also testified that it was concerning that Vossen wanted to plead not guilty despite the risk of conviction.

Gilbertson testified that Vossen wanted to clear his name and making a bad decision doesn't necessarily make you incompetent to stand trial, though he admitted that Vossen does have an issue with correctly citing dates of events.

Under cross-examination, both Aiken and Vaccarella agreed that it is rational for a person who is innocent to plead not guilty.


  • Competency hearing set for Vossen after evaluation declares him unable to assist in his defense against murder charge in 1974 Willmar homicide A competency hearing for Algene Vossen is set for June 18 after a Rule 20.01 competency evaluation declared him unable to assist in his defense. Vossen, 79, is charged with second-degree murder in the 1974 killing of Mabel "Mae" Agnes Boyer Herman in Willmar.
  • South Dakota man faces possible trial for a decades-old west-central Minnesota murder case

  • Cold case review in decades-old murder case leads to Willmar native Sioux Falls, South Dakota, resident Algene Leeland Vossen, 79, is awaiting trial for murder after a Willmar Police Department cold case review team zeroed in on him in 2020. A Willmar native, Vossen is charged in the January 1974 homicide of Mabel “Mae” Agnes Herman, 73, of Willmar, Minnesota.
  • Suspect charged in 1974 killing released from jail on medical furlough

  • Court hands down $1 million bail in Vossen case

An objection to exclude Vaccarella by Kandiyohi County Attorney Elizabeth Pierce was denied by Judge Wentzell.
Vaccarella, a licensed forensic psychologist in private practice, testified that she evaluated Vossen in July and determined Vossen has a neurocognitive disorder.


Vaccarella testified that Vossen has memory deficiencies, often repeating incorrect words in memory tests or giving nonsensical answers to questions.

"I think he can't be consistent," she said. She also said Vossen has the ability to do well in peaks but will often start falling back into memory issues on a longer timeline.

Aiken submitted a second report to the court, according to her testimony Friday, where she said that while there was an improvement in Vossen's demeanor and in some cognitive testing, she still found concern with Vossen's desire to plead innocent despite a lack a defense planning and "obvious deficits" in his understanding of court proceedings.

"He is incompetent (to stand trial)," Aiken testified Friday.

Aiken testified that Vossen's impairment was "moderate if not worse," citing Vossen's inability to cite correct dates and certain historical information. She did not have further testing to back that up.

"A full neuropsychological battery would be important," she said, something Vossen has yet to undergo.

Vaccarella testified that further testing may be helpful for Vossen's medical issues but that there are still "underlining brain changes" and further testing would not be relevant to cognitive decline.

Under cross-examination, she testified that, without further testing, the extent of Vossen's decline is unknown.

Aiken also called into question Gilbertson's report to the court and whether or not the answers given to Gilbertson from Vossen would lead to Gilbertson's conclusion that Vossen is able to stand trial.

"I do not believe those (answers) support a rational understanding (by Vossen)," Aiken testified, adding the lack of detailed descriptions in defense strategy or possible outcomes. She later testified that Gilbertson's report was not objective.

She called into question the use of Vossen's legal history, which is extensive, in Gilbertson's report. Gilbertson's diagnoses largely rely on Vossen's run-ins with the law and Vossen's inability to conform to societal standards.

Aiken testified that Gilbertson's diagnoses of "anti-social personality disorder with psychopathic traits or features with age-related decline" in Vossen was correct.

Aiken said that Gilbertson's conclusion confused her because Vossen's answer's showed a lack of understanding in Gilbertson's report, and Gilbertson's diagnoses do not have any bearing on cognitive decline.

Gilbertson testified that possible bereavement over the loss of his wife recently may have affected some of Vossen's cognitive ability, something with which Aiken largely agreed, but that that cognitive impairment would most likely still be present.

An earlier MRI showed "white matter" on Vossen's brain, something that has not been evaluated further, which Gilbertson and Aiken both said needed further testing.

While Vossen appeared in court Friday, he currently resides in Des Moines, Iowa, in the care of his niece, to seek medical treatment for various mental and physical disabilities, including dementia.

Read more of the West Central Tribune's coverage of Algene Vossen in the Mae Herman homicide in The Vault.

Mark Wasson has been a public safety reporter with Post Bulletin since May 2022. Previously, he worked as a general assignment reporter in the southwest metro and as a public safety reporter in Willmar, Minn. Readers can reach Mark at
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