There is no question that the Miranda warnings were given to the defendant before he made his statements to the police on September 4, 1975, and that those warnings were repeated before the defendant gave the police a complete confession on the following day. The only tenable basis for concluding that the statements or the confession were not made or given knowingly and voluntarily was the defendant's testimony that he had been under the influence of narcotics on both occasions. In the further findings made by him following the remand from this court, the judge characterized the defendant's testimony as incredible and expressly found (1) that the defendant was not under the influence of any narcotic on either occasion, (2) that he was capable of understanding and did understand the Miranda warnings, (3) that on both occasions he knowingly and voluntarily waived his right to remain silent, and (4) that on both occasions he was capable of understanding and did understand the questions put to him and his answers thereto. All those findings are amply warranted by the evidence, and there was no error in the judge's refusal to suppress the defendant's statements or his confession. Compare Commonwealth v. Sires, 370 Mass. 541 , 543-545 (1976); Commonwealth v. Fielding, 371 Mass. 97 , 103-113 (1976); Commonwealth v. Johnson, 371 Mass. 862 , 868-870 (1977); Commonwealth v. Black, 4 Mass. App. Ct. 512 , 516-517 (1976). Contrast Commonwealth v. Hosey, 367 Mass. 571 , 573-579 (1975), S.C. ante, 138 (1977).