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Elizabeth Holmes- Case Archive
personpersonMark BurnesMark BurnesPhysician who treated Mehrl Ellsworth and evaluated his conflicting prostate-specific antigen results.← All People
Expert witness

Mark Burnes

Physician who treated Mehrl Ellsworth and evaluated his conflicting prostate-specific antigen results.

AppearedFederal Criminal Trial
262 lines·8 proceedings·5 mentions

About

Mark Burnes testified for the government as an expert in PSA testing and interpretation. He described four tests obtained for his patient, Mehrl Ellsworth: three Theranos results of 26.1, 1.71, and 22.8, followed by a traditionally performed test returning 0.95. Burnes explained that he contacted Theranos, requested additional testing at the company's expense, lost confidence in the newer method, and concluded that the initial 26.1 result was invalid because it did not fit Ellsworth's earlier pattern or subsequent results.

An internal email attributed a possible sample-mixup explanation to Burnes, but he did not recall offering that explanation and did not identify the technical cause of the discrepancies. On cross-examination, he acknowledged that errors can occur before, during, or after laboratory analysis, that he had encountered switched patient results at another laboratory, and that different testing methods can produce different values. He nevertheless characterized significant PSA errors as rare, expected ordinary method-related variation to be modest, and disagreed with the professional screening recommendation presented to him.

On redirect, Burnes explained that he interpreted PSA results as a longitudinal trend rather than by relying on a single value or laboratory reference range. Although he agreed that a reported value of 26 was abnormal, he emphasized confirming a concerning result before further intervention. His testimony connected the disputed Theranos results with repeat testing, corrected reports, and his decision not to act until a result appeared valid.

Trial Record (8)

FederalFederal Criminal TrialAug 31, 2021 – Jan 3, 2022Called by prosecution

Mark Burnes testified for the government as an expert on PSA testing and interpretation, explaining why sharply inconsistent Theranos results for his patient prompted repeat testing and led him to regard the initial elevated result as invalid. Cross-examination and redirect addressed possible laboratory errors, method variation, screening guidance, and his reliance on trends and confirmation before intervention.

Day 35

DirectMark Burnes — DirectMark BurnesJeff Schenk5highlights131lines spoken

Summary

Physician Mark Burnes traced sharply conflicting Theranos PSA results for Mehrl Ellsworth, his requests for repeated testing, and later reports voiding two results. He opined that the initial 26.1 result was invalid.

Highlights (5)

rulingWithout defense objection, the court permitted Burnes to testify as an expert on diagnosing prostate cancer, PSA blood testing, and interpreting PSA results.Open in transcript →
testimony highlightBurnes compared a May 14 result of 26.1 with a May 18 result of 1.71, described the first as markedly higher than Ellsworth's prior pattern, and testified that he contacted Theranos and requested another test.Open in transcript →
Quote“WE DON'T USUALLY USE AN ISOLATED NUMBER BY ITSELF.”— Mark BurnesBurnes explained why a single PSA result should be evaluated against a patient's testing history rather than treated alone.Open in transcript →
testimony highlightBurnes concluded that the May 14 result was invalid because it did not fit Ellsworth's prior pattern and later results were near the expected range.Open in transcript →
Show all 5 highlights
Quote“I BELIEVE THAT TEST WAS INVALID.”— Mark BurnesBurnes gave his direct opinion on the accuracy of the May 14 Theranos result.Open in transcript →
CrossMark Burnes — CrossMark BurnesKatherine Trefz4highlights114lines spoken

Summary

Burnes acknowledged Theranos's early appeal, limited his reported use of its testing, and said he knew of no earlier Theranos problem besides Ellsworth's PSA result. He accepted that laboratory errors and method differences occur but characterized significant PSA errors as rare and expected ordinary variation to be small.

Highlights (4)

admissionBurnes estimated that about 10 percent of his total laboratory work went to Theranos, while roughly one-quarter to one-third of testing outside annual physicals may have gone there; he recalled no Theranos testing issue before 2015 other than Ellsworth's PSA result.Open in transcript →
rulingThe court permitted a narrowed question about switched patient samples after sustaining a broader relevance objection. Burnes acknowledged experiencing such an error elsewhere but described erroneous PSA results and unexpected laboratory errors generally as rare.Open in transcript →
Quote“YES, BUT THEY SHOULD BE VERY SMALL VARIATIONS. THEY SHOULD HAVE STANDARDS OF THE NORMAL RANGE ATTACHED TO EACH RESULT.”— Mark BurnesBurnes qualified the defense premise that different methods may produce different results by limiting the expected differences and emphasizing reference ranges.Open in transcript →
Quote“I AGREE WITH THE DISCUSSION WITH THE PATIENTS, BUT I DISAGREE WITH THE RECOMMENDATION.”— Mark BurnesBurnes distinguished his agreement that PSA screening should be discussed with patients from his disagreement with the professional guidance presented to him.Open in transcript →
RedirectMark Burnes — RedirectMark BurnesJeff Schenk4highlights17lines spoken

Summary

Burnes said Ellsworth's reported PSA value of 26 was abnormal but emphasized trends, repeat testing, and confirmation before further intervention.

Highlights (4)

testimony highlightBurnes explained that physicians should consider a patient's PSA trend, repeat a concerning result, and avoid further intervention until sufficiently assured that the result is valid.Open in transcript →
Quote“I WOULDN'T TAKE ANY ACTION UNTIL I FELT MORE ASSURED THAT WAS A VALID RESULT THAT WOULD WARRANT MORE INTERVENTION.”— Mark BurnesBurnes stated the clinical safeguard he would apply before acting on a concerning PSA result.Open in transcript →
testimony highlightBurnes characterized the reported PSA value of 26 as abnormal but emphasized that the rate of change can be more informative than whether a result falls inside or outside a laboratory reference range.Open in transcript →
Quote“THE RATE OF RISE IS WHERE YOU GET SUSPICIOUS.”— Mark BurnesBurnes distilled his view that a patient's PSA trend can matter more than the laboratory's stated reference range alone.Open in transcript →

Day 36

Day 39

ProceduralHearing on Renewed Motion to Admit Exhibit 14259Mentioned

Summary

The defense renewed its request to admit the E.T. test-results email as a business record. The government raised embedded-hearsay and foundation concerns, and the court deferred a ruling while considering redaction and further review.

Mentioned in this proceeding.

Day 47