Zapata County's sheriff Sigifredo Gonzalez has found blood on Tiffany Hartley's life vest, providing further evidence in support of her account of a pirate attack on a lake bordering Texas and Mexico.
U.S. officials have been searching for the body of David Hartley, but have been unable to retrieve it.
U.S. officials say the search for the American tourist reportedly shot dead on a border lake by Mexican pirates has been hampered by threats of an ambush from drug gangs.
U.S. Rep. Henry Cuellar of Texas said the search for David Hartley (of Loveland) was temporarily halted Wednesday evening as Mexican officials "worried about being ambushed because they've gotten the call already."
He said the search resumed Thursday morning, but Mexican searchers are "doing this under threat of their lives."
Gonzalez said the area where the shooting allegedly happened while Hartley and his wife were exploring the lake on jet skis is a stronghold of the Zeta drug gang. Gonzalez said he has sent word to Zetas that he wants the body returned and has no plans to prosecute.
Cuellar and two other area congressmen say Mexico was "doing the best that they can" even though Gov. Rick Perry has said drug-gang fears are no excuse to call off the search.
Friends and supporters of Hartley gathered for a rally in Denver Friday.
They assembled outside the Mexican consulate to bring attention to the case.
Colorado Gov. Bill Ritter said Friday that he's spoken with officials at the Mexican consulate in Denver. He says they've assured him that they're doing everything possible to find Hartley and bring those responsible to justice.