Glenn David Bauscher offers an English translation of the Syriac Peshitta translation of Genesis 4:15, which mentions the "mark" or "sign" of Cain.
Glenn David Bauscher, ed. The Holy Peshitta Bible Translated (electronic edition). Third ed. (Morrisville, NC: Lulu Press, 2019), accessed December 21, 2022
And LORD JEHOVAH laid a sign on Qayn, so that no one who finds him would kill him.