I don't know anything about a Wasiljew, but there was a Vasiliev (born in 1872) who was assigned to the Moscow Okhrana in 1900 and in 1910 to the Special Section of the Department of Police. He was close to extreme right wing groups such as the Black Hundred and was involved in instigating pogroms and publishing the notorious Protocols of the Elders of Zion. He became Chief of the Special Section of the Police in January 1917 but had to relinquish his post in March with the fall of the regime.
However, his name was Ivan Petrovich Vasiliev, so his initials were not A.T. Except for that, this would seem to be the person to whom you are referring. He was quite an unsavory character, capable of plots and counterplots against his colleagues to advance his own career.
If this is the person about whom you are seeking information, there is something on him in the book The Secret File of Josef Stalin: A Hidden Life, by Roman Brackman.
