He was most likely a Lithuanian Tatar or known as Lipka Tatars
Yes, I have heard of small Muslim populations, probably Tatars, existing in the Baltic region not that long ago, forming several villages.
The Mongol invasion ledt behind small populations of Mongol-type people in its wake as it receded. My father told me of a population in eastern German (now Poland) which he called "Wasser=Polacken
", or "Water Poles", which may have existed in the Masurian Lake region.