Appellee sued Mrs. Morgan for default in payment of a promissory note signed by her. After trial without a jury, judgment was entered for appellee from which the maker of the note has appealed.
Mrs. Morgan, a real estate broker and law school graduate, was the only witness who testified at the trial. According to her testimony, on August 16, 1960, one John D. Chamberlin, representing himself to be a Chicago private detective, and another man dressed in the uniform of the Metropolitan Police Department both wearing guns, appeared at her office with1 papers for the arrest of her brother, Kenneth Kennedy, who was then present. Chamberlin informed her that appellee had been a delivery man for the Walgreen Liquor Store in Chicago, that he had been indicted for stealing and transporting liquor, and that her brother was *84implicated. The brother, who had been in the liquor business in Chicago with another brother, Herman Kennedy, promptly denied he was involved. He admitted he had traded with Walgreen’s but denied he had ever received any liquor for which he had not paid.
In response to her inquiry as to what could be done, appellant was informed that if she would pay $5,000 they would let her brother remain in Washington. Upon her protest, this demand was ultimately reduced to a note for $1,500, payable in a year or eighteen months. The money was to be used, she was told, for legal or other expenses to defend the case in Chicago and to protect the interest of her brother. The men represented that unless she signed a note for this amount, they would be forced to take her brother back to Chicago. The brother told her then that she could sign the note if she wanted to do so, but that he would just as soon return to Chicago to defend himself. In any case, she signed the promissory note for $1,500 payable on March 1, 1962, to John D. Chamberlin at a named address in Chicago. It was subsequently endorsed by Chamberlin and delivered to appellee. There was no attempt or threat by the men to use their guns, but Mrs. Morgan stated she was in fear of them. Later appellant learned that neither Gilmer nor her brother had been indicted in Chicago. At the trial, she did not call her brother as a witness although he was in the city and available. She explained she did not think it was necessary.
In interrogatories answered by appellee under oath, inter alia, he stated that the note had been executed for a debt owed him by appellant’s brother Kenneth Kennedy and delivered to him by his agent, John D. Chamberlin; that it had not been obtained by any promise not to arrest or prosecute her brother; and that there had been no conspiracy between him and Chamberlin. An affidavit by Chamberlin, in opposition to a motion to dismiss the complaint, asserted that appellant had voluntarily executed the promissory note “for a valid and subsisting debt for the benefit of my principal * * * George Gilmer.”
Appellant primarily contends that the trial judge erred in not finding that duress and misrepresentation by Chamberlin and his companion forced her to sign the note and therefore vitiated any agreement to pay.
The critical issue of fact was the reason for the execution of the promissory note by appellant. Was the consideration a discharge of a valid debt owed by appellant’s brother to George Gilmer, for whom Cham-berlin was acting as agent, or was there in fact duress and fear which forced her to sign and execute the note?1
We have long recognized the principle that it is the exclusive function of the trial judge to determine the cogency and persuasiveness of the evidence and to weigh it for credibility, contradictions, reasonableness and evasiveness.2 Although he cannot refuse credence to testimony of a witness whose credibility is in no way impeached and whose testimony is reasonable and free from suspicion, he is not bound to accept the uncontradicted testimony of an interested party to the action.3
That the trial judge refused to accept appellant’s testimony concerning the purpose of the promissory note as credible and true is an inescapable conclusion. Having admitted the execution of the note, ap*85pellant had the responsibility to present as an affirmative defense acceptable proof that she had been induced by duress and misrepresentation to sign it. This she did not do, although her brother, who had full knowledge of the facts, could have been called to testify.4 His absence no doubt had a bearing on her credibility and upon the weight to be given her testimony.5
As we cannot say that the evidence was so compelling as to entitle appellant to a ruling in her favor on the issue of duress and misrepresentation invalidating the note given by her, we hold that the conclusion of the trial judge was neither plainly wrong nor without evidence to support it.6
Affirmed.
. Meisel v. Alexander, D.C.Mun.App., 111 A.2d 873; Rizzi v. Fanelli, D.C.Mun.App., 63 A.2d 872.
. Miller v. Imperial Insurance Incorporated, D.C.App., 189 A.2d 359, 360; Kuzminsky v. Wagner, D.C.Mun.App., 87 A.2d 411, 412.
. Tan Top Cab Company v. Shiller, D.C.Mun.App., 125 A.2d 68, 70; Barlow v. Cornwell, D.C.Mun.App., 125 A.2d 63, 67; Bowles v. Marsh, D.C.Mun.App., 82 A.2d 135; Johnson v. Hawkins, D.C.Mun.App., 81 A.2d 467, 469, citing Wynne v. Boone, 88 U.S.App.D.C. 363, 191 F.2d 220.
. Cherner v. Lawson, D.C.Mun.App., 162 A.2d 492.
. The conduct of a party in failing to produce an available absent witness may-give rise to an inference that the witness, if called, would not have been favorable to such party and is of a‘n impeaching char- . actor respecting the party’s proof,' unless the absence of such witness is satisfactorily explained. See Slenderella Systems, Inc. v. Greber, D.C.Mun.App., 163 A.2d 462, 464; Evans v. Bell, 49 App.D.C. 238, 240, 263 F. 634, 636; MacConnell v. Wood, 47 App.D.C. 424, 428; Maszczenski v. Myers, 212 Md. 346, 351, 129 A.2d 109, 114; Stocker v. Boston & M. R. R., 84 N.H. 377, 151 A. 457, 70 A.L.R. 1320, 1323.
. § 11-772 (c), D.C.Code, 1961.