BERLIN—Sources close to Tour de France-winning cyclist Jan Ullrich said Monday that the retired champion is beginning to feel that plastic bags of his blood may not be safe in the hands of anyone but himself after Spanish authorities found several of Ullrich's blood bags in the office of an infamous Spanish doping doctor. "Even long after I retire, sacks of my blood are still turning up in the strangest places," Ullrich, the only German to ever win the Tour, reportedly said to business associates. "You think your blood bags are safe with someone, and the next thing you know, aha! There it is in some Madrid refrigerator. Do I trust myself to people too easily, do you think?" Authorities in possession of the blood would not speculate on its origin, but photos posted on the Velo News website seem to show the inscription "To Lance And Sheryl, Best Wishes, Jan XOXO" on the seal of one bag.