TMZ has learned Tiger Woods' mother-in-law -- a prominent Swedish politician named Barbro Holmberg -- wasn't at Tiger's house during the Thanksgiving incident ... in fact, she just arrived in the States last Friday.
One of Tiger's neighbors told the Florida Highway Patrol both Elin's mom and Tiger's mom were at the crash scene. But we just spoke to Barbro's press secretary -- Eva Malmborg -- who confirms Barbro wasn't in the U.S. when it all hit the fan more than a week ago. A U.S. law enforcement source says she landed last Friday.
We're assuming she'll be doing a little comforting.