Updated

RAVERSE CITY, Mich.  -- Federal authorities say a father and son are charged with conspiring to threaten U.S. Rep. Bart Stupak and his family because of the Michigan Democrat's crucial vote for the health care overhaul.

The charges announced Monday followed an FBI investigation of a letter that said the writer would "paint" a Michigan bridge with the blood of Stupak and his family.

Federal prosecutors identify the suspects as 73-year-old Russell Hesch of West Branch, Mich., and 50-year-old David Hesch of Loveland, Colo.

Russell Hesch is being held in Michigan pending a detention hearing. Court-appointed attorney Robert Dunn says his client is "absolutely not guilty."

Authorities plan to appoint an attorney for David Hesch, who appeared Monday in federal court in Denver.