considering the claim presented by the beneficiary and the report furnished by the immediate superior; and

completing such investigation as he considers necessary.

Before review under section 8128(a) of this title, a claimant for compensation not satisfied with a decision of the Secretary under subsection (a) of this section is entitled, on request made within 30 days after the date of the issuance of the decision, to a hearing on his claim before a representative of the Secretary. At the hearing, the claimant is entitled to present evidence in further support of his claim. Within 30 days after the hearing ends, the Secretary shall notify the claimant in writing of his further decision and any modifications of the award he may make and of the basis of his decision.

In conducting the hearing, the representative of the Secretary is not bound by common law or statutory rules of evidence, by technical or formal rules of procedure, or by section 554 of this title except as provided by this subchapter, but may conduct the hearing in such manner as to best ascertain the rights of the claimant. For this purpose, he shall receive such relevant evidence as the claimant adduces and such other evidence as he determines necessary or useful in evaluating the claim.