delivered the opinion of the Court.
In People v. Ayala Ruiz, 93 P.R.R. 686 (1966), we expressed concern regarding the manner ill which' the inyes-. *334tigations, in which undercover agents intervened, were implemented by the police, and gave warning as to the necessity of improving the method of investigation to prevent the people from losing faith in justice and deriving the impression that the prosecution of certain persons who are linked with crime by reputation is sanctioned.1
We reaffirm now that there is a need for undercover police activity for the investigation of certain crimes, like the bolita, traffic in drugs, and the clandestine bancas. In the federal sphere, as recently as December 12, 1966, a similar view was enunciated in Lewis v. United States, 385 U.S. 206, but as it is properly stated therein “the particular circumstances of each case govern the admissibility of evidence obtained by stratagem or deception.” This is precisely the area we seek to explore in our pronouncements in People v. Ayala Ruiz, supra, and in the present opinion, being conscious that it is not possible to fix a rule of thumb to cover all the situations.
The experience in the District of Columbia helps us to place the problem in the appropriate perspective. The concern of the federal courts coincides with ours in the consideration of two basic factors which frequently occur in the-prosecution of these crimes, which are all characterized by their distinctive clandestinity: the delay in prosecuting the offenders and the sole testimony of the undercover agent. *335In Ross v. United States, 349 F.2d 210 (1965), the first expression on this particular, it is emphasized that the delay in commencing the proceeding — seven months — may be so onerous and oppressive that actually it may constitute a denial of the due process of law. Express reference is made to “The recurring spectacle of convictions based solely upon the testimony of a police witness, who, by reason of lapse of time, could not testify on the basis of unaided personal recollections . . . See also, Bey v. United States, 350 F.2d 467 (1965); Cannady v. United States, 351 F.2d 817 (1965); Jackson v. United States, 351 F.2d 821 (1965); Powell v. United States, 352 F.2d 705 (1965); Worthy v. United States, 352 F.2d 718 (1965); Roy v. United States, 356 F.2d 785 (1965); Daniels v. United States, 357 F.2d 587 (1966); and Morrison v. United States, 365 F.2d 521 (1966). Although it is true that defendant must show that he was prejudiced by the delay in filing the information, since this is the responsibility of the Government and it is arranged solely for its advantage, the accused should not be forced to labor under an exacting burden of proof. As stated in Jackson, supra often the difficulty encountered in establishing the elements of that prejudice is the best evidence of its existence. Since alibi is the usual defense presented it should not be forgotten that the majority of the offenders belong to a subcultural stratum characterized by the monotony of their daily existence and that this very absence of important events in their lives prevents them from distinguishing one day from another.
To correct these situations of manifest inequality the United States Court of Appeals in the District of Columbia invoked its inherent power to supervise the judicial proceedings. It is that same power of supervision which we now exercise. In cases of this nature the judicial role cannot be limited to determining the sufficiency of the evidence and the credibility of the witnesses. Aware of a situation of evident *336disadvantage for the accused we would be guilty of fetichism, if we would limit ourselves to closing our eyes to reality applying, with electronic precision, the doctrine of nonintervention in the weighing of the evidence. Our responsibility in a system of order and impartiality in the judicial proceedings is not fully accomplished by shifting the problem to legislative ambit; it demands that in the consideration of the appeals brought before us we require evidence to supplement the sole testimony of the undercover agent with something more than the minimum particulars necessary to establish the violation.2 We affirm that the particular circumstances of each case should govern not only the admission of evidence obtained by stratagem or deception, as stated by the Federal Supreme Court in Lewis v. United States, supra, but also the-effect of such evidence. It is not necessary, either, to vary the rule adopted in People v. Seda, 82 P.R.R. 695 (1961), for we had long since foreseen the inherent risks of a merely mechanical application thereof.
In the present case we confront once more a conviction of José Soto Zaragoza for a violation of the Bolita Act.3
*337On September 2, 19644 the prosecuting attorney filed an information against Soto Zaragoza and Carlos Palacio Ama-dor charging them with having, four months earlier, and on May 6, acting in accord and by mutual agreement, had in their possession and control material related to the illegal game of bolita. The arraignment took place on September 21, granting them a term to enter their plea, which they did by brief of November 6, informing that their defense was alibi. Upon defendant’s request the prosecuting attorney advised that he did not have any documentary evidence.
At the trial the only documentary evidence introduced consisted of the testimony of the undercover agent, Ramón Calderón, who testified that he had been stationed in Villa Palmeras area since about two and a half months before, to procure evidence of violations of the Bolita Act; and that in order to facilitate his work, he pretended to be a mechanic in the Sanjurjo brothers’ garage, situated four houses beyond the residence of codefendant Palacio; that on Wednesday, May 6, about 6:00 p.m. he was in front of Palacio’s residence and noticed that Soto arrived in a Buick and stopped in front of the house;..that he was about two or three feet away from the automobile, beside the fence of the house; that Palacio came out of his house and boarded the.automobile and sat by the side of Soto, at the right-front side, and talked to him for about five minutes, and then Soto took a package he had on the seat and delivered it to Palacio; that when Palacio opened the package he (the agent) noticed that it contained 3 digit figures with a space to the right and other figures; that then Palacio alighted from the car and entered his house; that after a few minutes Soto also entered the house where he remained for about fifteen minutes; that he cannot remember the figures.
*338On cross-examination he testified that subsequent to May 6, the date on which the facts occurred, he stopped working as undercover agent in Villa Palmeras area; that he was stationed away from San Juan, but he cannot remember the town; that that day it was dusky at 6:00 p.m.; to the question of whether his commission was to keep watch over Soto and Palacio exclusively, he answered affirmatively, and over other offenders too, but he admitted that as a result of his work only the latter, and no other person, was prosecuted; that the package was made up in wrapping paper, but he cannot remember the size; he admits that the sworn statement offered for the purpose of determining probable cause does not state that Palacio boarded Soto’s automobile; that Palacio passed in front of him when he went to Soto’s car; that he did not stoop to watch the delivery of the package; that the automobile did not have the interior light on; that there was no electric pole nearby, but there was light on the porch of the house; that Soto parked a “little” past the gate of the house.
Alberto Sanjurjo, witness for the defense, testified that he was the owner of the tinsmith and painting shop situated at 203 Merhoff Street in Villa Palmeras, to which agent Calderón alluded; that he knows the latter and that he never worked in his shop.
A slip for the Registration of Cockfights of the Public Recreation and Parks Administration corresponding to the fights held on May 6 in Gallera San Andrés was also introduced in evidence. Armando Santos, a professional cock breeder, who takes care of Soto’s cocks, testified that on said date fights were held in Gallera San Andrés, situated in Ward Caonillas in Carolina; that Wednesday is one of the cockfighting days during the season; that he brought three of Soto’s cocks; that he arrived at the cockpit at 9:00 a.m. accompanied by Soto, and they remained there until *339about 8:00 p.m., when both returned in Soto’s automobile; that Soto remained in the cockpit; that the fights are registered in the name of the cock breeder. From the registration slip it appears that Armando matched three fights, Nos. 9, 12 and 18. The bartender of the cockpit testified that Soto was in the cockpit that day from about 9:00 a.m. to 7:30 p.m., that he can remember the time he left there, because he went to him to pay the pending tickets.
It is proper to state previously that the time elapsed between the alleged commission of the offense and the presentation of the information — about four months — is not unreasonable and oppressive. Nor did it prejudice the appellants in the preparation of their defense of alibi.
Even more, a calm and objective examination of the evidence, causes great dissatisfaction in our conscience as to whether the defendants’ guilt has been established in the competent manner alluded to at the outset of this opinion. From the agent’s testimony it is inferred that he was expressly posted there to investigate Soto and Palacio. His version of the facts — the observation of the delivery of a package when it was dusky, inside of an automobile with no light on, and his perceiving, at a distance, a list of figures —although it establishes the minimum particulars of the offense charged, does not meet in itself, the requirements of the rule of exacting burden of proof to which we have previously alluded. We must add to this that he was contradicted as to the justification offered for his presence in that area — his work as a mechanic — and that Sanjurjo’s testimony was not impeached, and that the defense of alibi substantiated by parol and oral evidence had been timely notified to the prosecuting attorney, and although the prosecuting attorney had knowledge of the defense sought to be established, and of the evidence on which they intended to base *340said defense5 he did not present evidence of rebuttal either,- or contradict it in any manner whatsoever. The convictions-cannot prevail.6
The judgments rendered by the Superior Court, San Juan Part, on February 8, 1965 will be reversed.
Mr. Chief Justice Negrón Fernández, as well as Mr. Justice Belaval, concurs with Mr. Justice Santana Becerra in his dissenting opinion in this case.
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• ■ 1 Reports given to-publicity by the State Police tend to corroborate the existence of the practice to blacklist certain persons. In the edition of June 8, 1966 of the daily newspaper El Mundo, at p. 11, reference is made to the fact that “According to a survey made by the Police, there are in Puerto Rico, at the present time, 5,664 persons involved in the Bolita game and their operations cover 68 of the 76 towns in the Island. The survey, carried out as part of a general inventory of crime in the country, reveals that at least 350 of the 5,664 persons involved in the game are bankers and the remaining 5,314 are dealers who receive remuneration for their operations.”
See also the edition of April 5, 1967 of the newspaper “El Dm”; at p. 16.
The actions of the trial courts undoubtedly respond to the attitude previously assumed by this Court in affirming judgments of violations of the Bolita Act with the sole testimony of the undercover agent, generally a “slim and bare” testimony as we characterized it in People v. Ayala Ruiz, supra. In 1964 and 1965 of 39 appeals in bolita cases, we affirmed 35 and reversed the judgment in four occasions, two because of insufficiency of the evidence, one because of an illegal search, and one because we considered that there was entrapment. In 1966, prior to the decision in People v. Ayala Ruiz, supra, we affirmed the judgments in the fourteen appeals considered.
In People v. Soto, 71 P.R.R. 776 (1950), the sentence imposed could not prevail because the evidence introduced against defendant .was the result of an illegal search performed by the police. Two years later, in People v. Soto, 73 P.R.R. 52 (1952), we .affirmed an order of the trial court which had set aside a judgment of conviction on the ground that it was obtained by means of fraud committed by police officers.
The sworn statement- presented for the purpose of the determination of probable cause is dated August 24, three months 18 days subsequent to the occurrence of the facts charged.
The hearing was held on February 8, 1965, the defense of alibi was filed on November 16, 1964. Prior to the trial, December 23, 1964, the prosecuting attorney was notified of a motion for the summons of the person in charge of the record division of the Parks Administration with the records of the cockfights held May 6 at Gallera San Andrés. -
Although it has not been specifically assigned as error we noticed that the information filed does not allege that the material in appellants’ possession' relating to the bolita game could be used in said illegal' game or is connected with the practice of said game. See People v. Trinidad Fernández, 93 P.R.R. 877 (1967); People v. Mantilla, 71 P.R.R. 35 (1950) People v. De Jesús, 70 P.R.R. 36 (1949).