Angelina wants her blood back, fears a curse!
From the NY Daily News:
According to a source quoted in London's Sun, the actress is worried that Thornton, whose mom is a psychic, will "put a curse on her" using the blood: "He is a redneck and from a background experienced in these things. She wouldn't put it past him to try something like this and it scares her to death." The paper says Thornton took Jolie's blood from their Beverly Hills home in May.