The e-mail was sent to the Doug Flutie Jr. Foundation for Autism, based in Framingham, Mass.
Framingham police are trying to locate the sender, who they believe is in California, the Boston Herald reported.
"You jinxed the Longhorn faithful and a chance at the national title," Lt. Paul Shastany said describing a summary of the message.
"He was upset, wishing bad will and speaking badly about his (Flutie's) family," Shastany added. "At this point, the information is disconcerting enough to follow this up the best we can."
Kansas State beat the Longhorns Saturday in a 45-42 upset. Flutie, who won a Heisman Trophy in 1984 while playing for Boston College and went on to a professional career in the United States and Canada, appears on ABC and ESPN as an analyst of college football.