Section 755 ILCS 5/6-4 - Admission of will to probate - testimony or affidavit of witnesses(a) When each of 2 attesting witnesses to a will states that (1) he was present and saw the testator or some person in his presence and by his direction sign the will in the presence of the witness or the testator acknowledged it to the witness as his act, (2) the will was attested by the witness in the presence of the testator and (3) he believed the testator to be of sound mind and memory at the time of signing or acknowledging the will, the execution of the will is sufficiently proved to admit it to probate, unless there is proof of fraud, forgery, compulsion or other improper conduct which in the opinion of the court is deemed sufficient to invalidate or destroy the will. The proponent may also introduce any other evidence competent to establish a will. If the proponent establishes the will by sufficient competent evidence, it shall be admitted to probate, unless there is proof of fraud, forgery, compulsion or other improper conduct which in the opinion of the court is deemed sufficient to invalidate or destroy the will.(b) The statements of a witness to prove the will under subsection 6-4(a) may be made by (1) testimony before the court, (2) an attestation clause signed by the witness and forming a part of or attached to the will or (3) an affidavit which is signed by the witness at or after the time of attestation and which forms part of the will or is attached to the will or to an accurate facsimile of the will.