Federal agents have raided the home of the mother-in-law of Barry Bonds' personal trainer Greg Anderson.

Madeleine Gestas is the target of a tax investigation that Anderson's lawyer says is aimed at pressuring the trainer to testify at Bonds' upcoming trial on charges on lying to a grand jury.

Mark Geragos, a lawyer for Anderson, said he believes the raid Wednesday is in response to his refusal to tell prosecutors whether Anderson would testify.

Anderson served more than a year in prison for refusing to testify against Bonds before a federal grand jury.

Geragos said Anderson received a government subpoena last week demanding his testimony at trial. If he refuses to testify, he could be sent to prison again.