In the last years of his life, William Shakespeare was an elegant gentleman who spent time at his Stratford residence, sitting on an elaborately carved chair in the company of a book and an adoring dog.

About two decades earlier, he was a relatively young man exuding self-confidence and proud smiles.

These powerful images emerge from two previously unknown portraits of Shakespeare, according to Hildegard Hammerschmidt-Hummel, a professor of English at Mainz University, Germany.

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"I subjected the images to fundamental tests of identity and authenticity, and these revealed that we are dealing with true-to-life portraits of Shakespeare, one from his youth, the second from his old age," Hammerschmidt-Hummel told Discovery News.

She announced the new finding this morning at a press conference at Mainz Cathedral.

According to the German academic, one portrait, possibly painted around 1594, when the poet was about 30 years old, depicts Shakespeare as a young London playwright and author of sonnets who has reached the first height of his unparalleled literary career.

"Showing amazing self-confidence, the man appears to cast his spell over the viewer with a touch of a triumphant smile," Hammerschmidt-Hummel said.

Hung in the bedchamber of Prince Franz (1740-1817), in the Gothic House of the Dessau-Wörlitz Garden Realm, the 2.4- by 2-foot portrait was seized in 1945 by the Soviet army.

"It has been lost ever since. Today there is only a high-quality, monochrome photograph from 1936, now in the Photo Marburg Picture Archive," Hammerschmidt-Hummel said.

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Archival research shows Prince Franz brought the picture from his trip to England from 1763 to 1764. Records show it was given to him as a gift by Thomas Hart, a distant relative of Shakespeare.

While the Wörlitz portrait only depicts Shakespeare's facial features, the second portrait shows the whole person of Shakespeare for the first time.

"We can see he wasn't a very tall man," Hammerschmidt-Hummel said.

The painting is estimated to show Shakespeare at the age of 50, about two years before his death and it portrays the Bard as an affluent, older gentleman living in retirement. He sits on an elaborately carved chair, holding a a book in his left hand and resting his right hand on the head of a dog, which is sitting to his right.

Two New Portraits of Shakespeare Found: Page 2

The two new portraits: the Wörlitz portrait (left) and the Boaden portrait (right).Hammerschmidt-Hummel

Careful examination of the image has even determined the breed of the dog, which, according to the London veterinary Bruce Fogle, appears to be a Lurcher, (a cross between a Greyhound and a working dog). Little is known about the provenance and history of the portrait.

"I am calling it the Boaden Portrait because I found it in a rare, richly illustrated edition of James Boaden's work of 1824," Hammerschmidt-Hummel said.

Called "An Inquiry into the Authenticity of Various Pictures and Prints, which ...have been offered to the Public as Portraits of Shakespeare," the book displays the portrait as an engraving -- with no caption.

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"Nevertheless, my research in close interdisciplinary collaboration with experts from other disciplines shows we are dealing here with an authentic portrait," Hammerschmidt-Hummel said.

"The portrait could only have come about by direct contact of the artist with his model, that is Shakespeare," said Jost Metz, a dermatologist who examined the portraits. Metz specializes in diagnosing signs of disease in Renaissance portraits.

Announced on the 450th anniversary of the poet's birth, the new finding adds to four portraits of the Bard which Hammerschmidt-Hummel authenticated in 2006 amid some controversy.

Before then, only two likenesses of Shakespeare, both posthumous, were accepted as authentic: a bust on his tomb in Stratford's Holy Trinity Church and an engraving shown in the Folio edition of his plays in 1623.

To authenticate the two new portraits, Hammerschmidt-Hummel used four images that had already been thoroughly tested by various experts and found to be genuine, as well as the two accepted likenesses: the Darmstadt Shakespeare death mask, the Davenant bust, the Chandos and the original Flower portraits. She authenticated the four portraits back in 2006.

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The experts used forensic imaging technologies, 3D-measurements, laser-scan images and computer montages to compare the pictures.

The tests for authenticity on the new portraits brought to light a series of facial marks and idiosyncrasies that correspond to those found on all the other Shakespeare likenesses. In particular, the two newly found pictures show a growth on the upper left eyelid and swellings in the nasal corner of the left eye, which seem to represent different stages of a disease.

"Renaissance painters faithfully reproduced not only the features of their subjects, but also any signs of disease," Hammerschmidt-Hummel said.

A team of doctors analyzed both paintings and concluded that, in the Boaden portrait, the Mikulicz's syndrome and the additional swelling on the upper left eyelid, interpreted as lymphoma by the ophthalmologist Walter Lerche in 1995, had grown considerably.

The doctors say that the swelling on the left upper eyelid of the Wörlitz picture is just appearing and less noticeable.

With reference to the nasal corner of the left eye of both new portraits, Metz, the dermatologist, stressed that this was a pathological symptom all the authentic images had in common.