I checked the Lithuanian telephone directory and didn't find anything close except for one person with the spelling of:

Regina Fasputėnienė

The IENE ending is a married female spelling. There is no listing for a male with the family surname spelling. It's common in Lithuania for the home phone to be in the wife's name.

Likely we need to find out documents with other variations in surname spelling to get closer to the original spelling.

Tom S.