[Below I will give a very brief account of Stephen C. Carlson's case regarding the handwriting of the Theodore-letter, found in Carlson 2005, 23-47.
-According to Morton Smith and the experts he consulted, the Theodore-letter was written during the 18th-century, c. 1750 +/- 50 years.1 Carlson contests this consensus: Smith does not tell us how brief the expert consultation was, or from how detailed photographs was it conducted, and thus the examination of the handwriting is best to perform afresh, from the beginning.2
-A part of the method canon of the forensic science, Questioned document examination (QDE), is consistently used in court in the USA (and elsewhere). Applying QDE Carlson observes various signs of a forgery including "forger's tremor", blunt pen ends, unnecessary pen lifts, and letter fixing - in QDE, these features occur when the handwriting is not the writer's natural one, when the writer has to actually draw the letters (instead of writing them) to get the handwriting look something else than his own. More precisely, according to Carlson, both the problems of the line quality and the fixing of the letters afterwards should not occur within the same document; though the first is plausible in situations of stress, old age, or fatigue, who would have done the fixing afterwards? His conclusion: the Theodore-letter is a drawn imitation of an 18th-century hand.3
-Other odd features noted by Carlson: the Theodore-letter differs from other Mar Saba MSS of the same age in its letter forms (e.g. lambda in other MSS is always written with a single stroke, in the Theodore-letter this varies between one and two strokes), in its use of nomina sacra, in its beginning with a sign of the cross4, and in its use of a narrow pen point.5
-Furthermore, Carlson identifies the handwriting of the Theodore-letter to be the same as the handwriting of Morton Smith himself (comparing the letter to two pages with remarks written in Greek by Smith in the margins). Carlson argues that the letters lambda, theta and tau are too similar between the letter and Smith's marginal notes to be a coincidence (e.g. in theta both start with a short horizontal line beginning from the left, from about the middle of the letter).6
-Going even further, Carlson gives the first elaborate clue argument (these are assessed in detail in Chapter 2.5 (Madiotes-clue) and in Chapter 4), claiming that Smith hid a deliberate clue of his identity to another MS found in Mar Saba, using a pseudonym Μ. Μαδιότης as a clever way to refer to himself as a "bald swindler" - he was bald, after all, and if he composed the Theodore-letter, he was also a swindler.
In more detail: Morton Smith published a catalogue in 1960 of the MSS he found visiting the monastery two years earlier, with 76 titles.7 A photograph of the MS number 22 was used by Smith twice in his later publications, in his 1960 article "Monasteries and Their Manuscripts" published in Archaeology, and in his 1973 book "The Secret Gospel". From this vertically cropped photograph8 Carlson concludes, utilizing also the 1960 catalogue's description9, that there were three different handwritings to be found in folio 1, recto. The uppermost handwriting was, according to Carlson, assessed to have been from the 20th-century by Morton Smith himself.10 However, Carlson estimates the handwriting to be from the 18th-century, and moreover, to be the exact same handwriting as that of the Theodore-letter, including forger's tremor, narrow pen point, and blunt line endings.11
According to Carlson, the personal name Μ. Μαδιότης (not seen in the photograph but found in Smith's description in the 1960 catalogue) is to be associated with this handwriting of the Theodore-letter, found in MS22. Without a religious title the person in question must have been a visitor to the monastery, but the surname Μαδιότης is not found from a Greek online-directory. However, there is a verb in modern Greek, μαδάω, that has two very suitable meanings for a pseudonymous use (the verb μαδάω, if one wanted to come up with a fictitious Greek surname based on the verb, could be used to form something like Μαδιότης), literally it means "to bald", and figuratively "to swindle". M[orton] Μαδιότης is a pseudonym of Morton Smith, the bald swindler, deliberately left as a clue for the writer's true identity.12
From various famous forgeries, Carlson concludes (citing Anthony Grafton's "Forgers and Critics: Creativity and Duplicity in Western Scholarship" as authoritative) that hoaxes (differentiated here from mere forgeries) are characterized by witty clues left by the writer for the possible unearthing of his true identity. Thus, if the Theodore-letter is a hoax by Morton Smith (whose rather eccentric sense of humour is well attested by many hilarious anecdotes), it must be saturated with wit and ingenious nods towards Smith's, the hoaxer's, true identity.13 Like the Madiotes-clue presented above.]
1Smith 1960a, 251-252; Smith 1973, 1; Smith 1985, 22-25.
2Carlson 2005, 23-25.
3Carlson 2005, 25-32.
4Carlson even suggests this to be another deliberate clue left by Smith of his identity: the sign of the cross or crux critica is used in textual criticism to mark spurious text!; Carlson 2005, 33.
5Carlson 2005, 25-33, 46.
6Carlson 2005, 46-47.
8The photograph of MS22 in Smith 1960b was cropped vertically so far so that half(!) of the essential page (folio 1, recto) was missing. In "The Secret Gospel" there would have been some more recognisable letters to be seen, but for some reason Carlson does not utilize this instead.
9Smith 1960a, 119-120.
10Smith 1960a, 119-120.
11Carlson 2005, 42-43.
12Carlson 2005, 43.
13Carlson 2005, xviii, 16.