Actually, this uknown agent was known as, "Mega".
Hard to say. 1985 was "the year of the spy" and over 1985-86 a classified but very high number (closer to 100 than zero) of sources in the USSR and Soviet Bloc were recalled to Russia and, mostly, executed. By January 1987 we were down to bupkus in terms of practical human sources in that part of the world. Not all these sources were fully recruited agents (probably a distinction w/o a difference to the lay person).
There were also significant diminutions in take from technical operations in that period.
The question is, who died because of Pollard? In 1985 not just Pollard, but Edward Howard, Aldrich Ames, Ronald Pelton, Army Warrant Officer James Hall, air force gay blade Jeffrey Carney, and the John Walker syndicate all gave up significant data directly to Soviet handlers. Others such as Sharon Scranage gave the data to 3rd parties who passed it to their Soviet liaisons or handlers. Pelton, Hall and Carney mostly compromised technical operations, and Howard, Ames and Scranage mostly gave up human sources. Walker gave up code machinery which has consequences for all kinds of operations. There were other rings active during this period that targeted military information.
So... with all these traitors active, only the CIA and FBI have a prayer of figuring out which intelligence operation was compromised by which traitor. A better way of seeing it might be: we don't know if Pollard got anyone killed, but we know he might have done.
And we know he didn't care if he did.
d.o.l.
Criminal Number 18F