Defendant pleaded guilty to the crime of attempted robbery in the third degree (Penal Law, §§ 110.00, 160.05). The judgment of the Supreme Court, Bronx County, rendered upon his plea, was unanimously affirmed by the Appellate Division. Defendant claims on this appeal that he was deprived of the right to a speedy trial, guaranteed to him by the Sixth Amendment of the United States Constitution and CPL 30.20 (formerly Code Crim Pro, § 8). The precise issue before us is under what circumstances the defendant’s incar*125ceration in a sister State justifies a delay in bringing him to trial in New York.
Defendant was indicted by the Bronx County Grand Jury on September 30, 1968 and charged with the crimes of robbery in the first degree, grand larceny in the third degree and possession of a weapon. He was released on bail and directed to appear in Bronx County Supreme Court on December 20, 1968. On December 13, 1968, however, defendant was arrested in New Jersey and charged with having committed the crimes, of kidnapping, rape, carnal indecency and unlawful possession of narcotics, for which he was later indicted, convicted and sentenced to serve between five and seven years in New Jersey State prison. He remained in the custody of the New Jersey authorities until June 25, 1972 when, under a detainer filed pursuant to the provisions of CPL 580.20, he was released to the custody of Bronx County authorities.
Defendant moved, on October 17, 1972, to dismiss the Bronx County indictment on the ground that he had been denied the right to a speedy trial. In the motion papers, consisting solely of an affidavit made by defendant’s counsel, it was alleged, upon information and belief, that shortly after the defendant’s arrest in New Jersey, the New York authorities filed a detainer on him but made no effort to secure his presence in New York or prosecute the indictment. No facts in support of this claim were set forth as required by CPL 210.45.1 In his opposing affidavit the District Attorney stated that delay "has not been the fault of the People as defense counsel alleges in his papers.” Without a hearing and on defendant’s meager unsupported allegations in the motion papers alone, the court conditionally granted the motion on December 5, 1972 and directed that the indictment be dismissed if the People did not commence trial before January 15, 1973. However, six days following the entry of this order, defendant entered a plea of guilty to the crime of attempted robbery in the third degree in full satisfaction of the original indictment.
*126It is settled that delay occasioned by the defendant’s incarceration under the jurisdiction of the Federal Government or another State is not justified when prosecutorial authorities have knowledge of the defendant’s detention and make no diligent efforts to obtain his presence for trial (Smith v Hooey, 393 US 374, 383; People v Wallace, 26 NY2d 371; People v Winfrey, 20 NY2d 138). It is thus incumbent upon the People to show that the defendant has not been brought to trial for "good cause” (People v White, 32 NY2d 393, 397; People v Wallace, supra; People v Winfrey, supra; People v Bryant, 12 NY2d 719; see, also, former Code Crina Pro, § 667). Prefatorily, of course, knowledge of the defendant’s whereabouts by law enforcement authorities must be established. Knowledge on the part of the police department would, of course, be imputed to the District Attorney’s office. A defendant ought not be penalized because of any inadequacy of internal communication within the law enforcement establishment (cf. Santobello v New York, 404 US 257, 259-260).
The insufficiency of the record before us makes it impossible to determine whether a reasonable basis for the delay was present. The New Jersey incarceration may provide the requisite "good cause” if the prosecutor was unaware that the defendant was in the custody of the authorities of a sister State and could not with due diligence discover the defendant’s whereabouts and secure his presence for trial in New York.2
Both the District Attorney and defendant’s counsel attempted, during the course of the judicial process below, to introduce documentary evidence relating to the issue of the prosecutor’s knowledge of defendant’s imprisonment in New Jersey. In fact, the District Attorney was precluded, on defendant’s objection, from showing that a reasonable basis did *127exist for the delay. He had sought to introduce evidence that the Bronx County authorities were not aware of defendant’s incarceration in New Jersey until May, 1972. Thus, it cannot be charged that the law enforcement establishment failed to fulfill its obligation to justify the delay.
We have concluded that a proper resolution of this appeal requires a more complete record. This case comes to us in a peculiar stance. There was no opportunity to make a complete record below since (1) there was no hearing on the original motion to dismiss the indictment, which was granted conditionally, (2) defendant decided to plead guilty and (3) the prosecutor was prevented from introducing evidence relating to the point in time when it was first known that defendant was in custody in New Jersey.
It is apparent from the condition on which defendant’s motion to dismiss was granted that the Trial Judge granted the motion on the basis of the period of delay commencing with the time of defendant’s return to New York (June 26, 1972).3 He did not base his decision on the period of imprisonment in New Jersey. The record, by way of documentary proof, should be made complete. On remand, both sides will have the opportunity to come forward with the documentary evidence which they were unable to introduce below (see CPL 210.45, subds 1, 2). Therefore, the determination of this appeal should be withheld4 and the case remitted to Supreme Court, Bronx County, for the presentation of documentary evidence pertaining to the knowledge of New York law enforcement authorities of defendant’s incarceration in New Jersey and the efforts of the police and prosecutorial authorities to secure defendant’s presence in New York following notice of his status.
Chief Judge Breitel and Judges Jasen, Jones, Wachtler, Fuchsberg and Cooke concur.
Determination of the appeal withheld and the case remitted *128to Supreme Court, Bronx County, for further proceedings in accordance with the opinion herein.