By Ariel David, The Associated Press

ROME - A Vatican researcher has rekindled the age-old debate over the Shroud of Turin, saying that faint writing on the linen proves it was the burial cloth of Jesus.

Experts say the historian may be reading too much into the markings, and they stand by carbon-dating that points to the shroud being a medieval forgery.

Barbara Frale, a researcher at the Vatican archives, says in a new book that she used computer-enhanced images of the shroud to decipher faintly written words in Greek, Latin and Aramaic scattered across the cloth.

She asserts that the words include the name "(J)esu(s) Nazarene" - or Jesus of Nazareth - in Greek. That, she said, proves the text could not be of medieval origin because no Christian at the time, even a forger, would have mentioned Jesus without referring to his divinity. Failing to do so would risk being branded a heretic.

"Even someone intent on forging a relic would have had all the reasons to place the signs of divinity on this object," Frale said Friday. "Had we found 'Christ' or the 'Son of God' we could have considered it a hoax, or a devotional inscription."

The shroud bears the figure of a crucified man, complete with blood seeping from his hands and feet, and believers say Christ's image was recorded on the linen's fibers at the time of his resurrection.

The fragile artifact, owned by the Vatican, is kept locked in a protective chamber in a Turin cathedral and is rarely shown. Measuring 13 feet (four meters) long and three feet (one meter) wide, the shroud has suffered severe damage through the centuries, including from fire.

The Catholic Church makes no claims about the cloth's authenticity, but says it is a powerful symbol of Christ's suffering.

There has been strong debate about it in the scientific community.

Skeptics point out that radiocarbon dating conducted on the cloth in 1988 determined it was made in the 13th or 14th century.

But Raymond Rogers of Los Alamos National Laboratory said in 2005 that the tested threads came from patches used to repair the shroud after a fire. Rogers, who died shortly after publishing his findings, calculated it is 1,300 to 3,000 years old and could easily date from Jesus' era.

Another study, by the Hebrew University, concluded that pollen and plant images on the shroud showed it originated in the area around Jerusalem sometime before the eighth century.

While faint letters scattered around the face on the shroud were seen decades ago, serious researchers dismissed them, due to the results of the radiocarbon dating test, Frale told The Associated Press.

But when she cut out the words from enhanced photos of the shroud and showed them to experts, they concurred the writing style was typical of the Middle East in the first century - Jesus' time.

She believes the text was written on a document by a clerk and glued to the shroud over the face so the body could be identified by relatives and buried properly. Metals in the ink used at the time may have allowed the writing to transfer to the linen, Frale said.

She said she counted at least 11 words in her study of enhanced images produced by French scientists in a 1994 study. The words are fragmented and scattered on and around the image's head, crisscrossing the cloth vertically and horizontally.

One short sequence of Aramaic letters has not been fully translated. Another fragment in Greek - "iber" - may refer to Emperor Tiberius, who reigned at the time of Jesus' crucifixion, Frale said.

She said the text also partially confirms the Gospels' account of Jesus' final moments. A fragment in Greek that can be read as "removed at the ninth hour" may refer to Christ's time of death reported in the holy texts, she said.

In her book "The Shroud of Jesus Nazarene," published in Italian, Frale reconstructs from the lettering on the shroud what she believes Jesus' death certificate said: "Jesus Nazarene. Found (guilty of inciting the people to revolt). Put to death in the year 16 of Tiberius. Taken down at the ninth hour."

She said the text then stipulates the body will returned to relatives after a year.

Frale said her research was done without the support of the Vatican.

"I tried to be objective and leave religious issues aside," Frale told the AP. "What I studied was an ancient document that certifies the execution of a man, in a specific time and place."

Frale's work usually focuses on medieval documents. She is noted for research on the order of the Knights Templar and her discovery of unpublished documents on the group in the Vatican's archives.

Earlier this year, she published a study saying the Templars once had the shroud in their possession. That raised eyebrows because the order was abolished in the early 14th century and the shroud is first recorded in history around 1360 in the hands of a French knight.

Her latest book on the shroud raised even more doubts among some experts.

On one hand, it is true that a medieval forger would label the object with Christ's name, as were all relics produced at the time, said Antonio Lombatti, a church historian who has written about the shroud. The problem is that there are no inscriptions to be seen in the first place.

"People work on grainy photos and think they see things," Lombatti told the AP. "It's all the result of imagination and computer software. ... If you look at a photo of the shroud, there's a lot of contrast between light and dark, but there are no letters."

Further criticizing Frale's work, Lombatti said that artifacts bearing Greek and Aramaic texts were found in Jewish burials from the first century, but the use of Latin is unheard of.

He also rejected the idea that authorities would officially return the body of a crucified man to relatives after filling out some paperwork. Victims of that form of execution used by the Romans would usually be left on the cross or were disposed of in a dump to add to its deterrent.

Lombatti said "the message was that you won't even have a tomb to cry over."

Another shroud expert, Gian Marco Rinaldi, said that even scientists who believe in the relic's authenticity have dismissed as unreliable the images on which Frale's study was based.

"These computer enhancements increase contrast in an unrealistic way to bring out these signs," he said. "You can find them all over the shroud, not just near the head, and then with a bit of imagination, you see letters."

Unusual sightings in the shroud are common and are often proved false, said Luigi Garlaschelli, a professor of chemistry at the University of Pavia. He recently led a team of experts that reproduced the shroud using materials and methods available in the 14th century - proof, they said, that it could have been made by a human hand in the Middle Ages.

Decades ago, entire studies were published on coins purportedly seen on Jesus' closed eyes, but when high-definition images were taken during a 2002 restoration, the artifacts were nowhere to be seen and the theory was dropped, Garlaschelli said.

He said any theory about ink and metals would have to be checked by analysis of the shroud itself.

The last public display of the shroud was in 2000, when more than 1 million people turned up to see it. The next is scheduled for 2010, and Pope Benedict XVI has been asked to visit it.