Telltale Signs of Picasso's Art

In his book The Cell's Design: How Chemistry Reveals the Creator's Artistry, Fanzale Rana gives the following account of the approach used to authenticate a piece of artwork by Picasso, often referred to as The Unknown Masterpiece:
In the early 1970s, a junk dealer came across five ink drawings while clearing out a deceased woman's apartment in London. He hung onto them for several years, [and then] one of them wound up in the hands of a Brighton art dealer. Eventually, that dealer showed the mysterious drawing to Mark Harris, an art aficionado, who concluded that the piece might well be an unknown work by Picasso.
This drawing, referred to as Picasso's The Unknown Masterpiece, has provoked a heated controversy between his estate and Harris. The estate and its beneficiaries deny the drawing's authenticity.
In the face of this rejection, Harris and his collaborators began amassing … evidence to support their claim that Picasso, indeed, painted the masterpiece.
To make the case, Harris points to hallmark features of Picasso's work. For example, a fingerprint rolled into the wet ink at the time the drawing was made appears near the bottom of the piece. Many artists in the early 1900s, including Picasso, began fingerprinting artwork to stave off fraud. This mark would conclusively identify the work as a Picasso if compared with his known fingerprint. However, the estate refuses to comply, officially insisting that Picasso did not fingerprint his work during the 1930s.
While photographing the painting, Harris also discovered what seems to be Picasso's dated signature. A Scotland Yard handwriting expert identified features in the signature consistent with those from Picasso's works.
The drawing also contains a number of features characteristic of other Picasso works and appears to have connections to several pieces. Both Mark Harris and Melvin Becraft … place Picasso's The Unknown Masterpiece between his 1925 work, The Three Dancers, and his 1937 work, Guernica. Picasso was known to carry ideas and themes from work to work. The Unknown Masterpiece links themes, symbolisms, and hidden imagery in The Three Dancers with those in found in Guernica—connections not previously apparent.
Harris also recognised themes that reflect the events of Picasso's life at the time The Unknown Masterpiece was created. The year 1934 was a time of intense crisis for Picasso. The tragedies he experienced appear in the imagery of the mysterious drawing. Related symbolism depicting these circumstances also occurs in other Picasso pieces of the same history.
It remains to be seen if Harris's case for authenticity convinces the Picasso estate and the art world. Still, he has assembled what appears to be a compelling argument on the painting's behalf.

Fanzale Rana, The Cells' Design: How Chemistry Reveals the Creator's Artistry (Baker Books, 2008), pp. 23-24