In early 1979, a manila envelope arrived at Walter McCrone’s Chicago laboratory, containing what would become the most controversial samples of his career.

Inside were adhesive tape strips taken from the Shroud of Turin—a centuries-old linen cloth believed by many to be the burial shroud of Jesus Christ. What McCrone discovered on these samples ignited a scientific and religious firestorm that would follow him for the rest of his life.

Walter Cox McCrone Jr., born in 1916, was a pioneering chemist and microscopist. His expertise in polarized light microscopy and chemical analysis made him a sought-after authority in forensic science and art authentication. He built a renowned laboratory and research institute, teaching thousands of students and publishing hundreds of articles.

McCrone’s reputation for exposing forgeries led to his involvement with the Shroud of Turin Research Project (STRP) in the late 1970s. The project brought together top scientists to analyze the shroud using advanced techniques.

In 1978, with permission from the Catholic Church, the team collected samples from the shroud—including the tape strips McCrone would later examine.

Using polarized light microscopy and electron microanalysis, McCrone meticulously studied the samples. He found that the faint sepia image on the shroud was composed of billions of microscopic pigment particles—specifically red ochre (iron oxide) and vermilion (mercuric sulfide)—distributed in patterns consistent with deliberate painting.

Most notably, forensic tests for blood on the supposed “blood stains” returned negative results. To confirm his findings, McCrone conducted experiments with linen, painting with both red ochre and diluted blood, and found that only the pigment produced results identical to the shroud samples.

In 1980, McCrone published his conclusion: the Shroud of Turin was not a miraculous relic but a medieval painting created around 1355, just before its first recorded appearance.

Historical records supported this, including a French bishop’s claim that the shroud was a forgery and that he knew the artist. McCrone’s analysis suggested the image was made with a technique similar to those used by 14th-century European artists.

His findings were met with fierce resistance. Other members of STRP, using different tests, claimed to find evidence of blood and disputed the presence of pigments in sufficient quantities.

The disagreement became intensely personal and divisive, with McCrone’s critics questioning his methodology and his decision to publish in his own journal. Nonetheless, McCrone’s data was never proven fraudulent, and some art conservation experts and renowned scientists supported his conclusions.

Vindication came in 1988, when radiocarbon dating was performed on samples from the shroud by three independent laboratories. The results dated the linen to between 1260 and 1390 CE—matching McCrone’s prediction and confirming the shroud’s medieval origin. Despite this, controversy persisted. Believers challenged the dating, arguing the samples were taken from a repair patch or contaminated by later events.

McCrone stood by his findings until his death in 2002, never recanting. He argued that science must follow the evidence, regardless of popular opinion or religious sentiment.

His work revealed the challenges of scientific inquiry when faith and emotion are involved, highlighting the need for transparency, collaboration, and open debate.

More than two decades after McCrone’s death, the Shroud of Turin remains a subject of fascination and controversy. While his analysis and the radiocarbon dating strongly support a medieval origin, questions about the image’s formation and the shroud’s history endure. McCrone’s legacy is one of rigorous scientific methodology, courage in the face of criticism, and a reminder that sometimes, the search for truth uncovers more questions than answers.