delivered the opinion of the Court.
The appellant was tried and convicted on lottery and bookmaking charges and was sentenced to fines aggregat*55ing $1100, and costs, and imprisonment for a year. He appeals. The principal question at issue is the validity of his arrest, since the legality of the search of his person which produced the evidence upon which he was convicted depends upon the legality of his arrest.
On January 9, 1954, shortly before 8:30 P.M., Detectives Kemple and Morsberger of the Baltimore City Police Department went to the appellant’s place of business in Baltimore to “pick him up” for investigation on account of a burglary which had occurred on January 4th. They had no warrant for his arrest. The police officers entered the premises and went to the door of the traverser’s office. The door was open a little way, and Sergeant Kemple testified that he saw the traverser sitting at a desk and working on some papers, the nature of which the Sergeant did not then know. Kemple called to the traverser, who recognized him; and in reply to Kemple’s statement that he wanted to see him a minute, the traverser said “Come on in.” Kemple and Morsberger then entered the office with Kemple in the lead. Kemple further testified that as he walked up alongside the desk, he noticed some papers on it and that he “noticed the name ‘Tip-off’, then a dash and 2 dash DD” and that from his experience as a former member of the Vice Squad he knew that this notation “was part of a daily double horse racing bet.” When the traverser saw the police officer looking at these papers he picked them up and put them in his pocket. The second officer testified that he was not able to see what was written on the papers which the traverser put in his pocket. While there are some minor differences in the testimony of the two officers, we find no serious discrepancy. The principal difference is that the officer, who entered behind the sergeant, naturally could not see so much.
The two police officers took the appellant to a police station where he was booked on the arrest register as “Held for investigation. Charge, Burglary.” There was no notation at that time of any other charge. The appel*56lant was then searched and numerous papers containing notations of race horse bets and lottery numbers were found on his person and were seized by the police. In some wholly unexplained manner this documentary evidence disappeared, and none of it was produced at the trial, though several officers testified to the nature of the papers.
The rule is well established that if a misdemeanor is being committed in the presence or view of a police officer he may forthwith arrest the offender without a warrant, and that an offense is committed in his presence or view if, through his senses, he has knowledge of facts or circumstances sufficient to justify a sincere belief that the accused is committing the misdemeanor in his presence. Griffin v. State, 200 Md. 569, 92 A. 2d 748; Kershaw v. State, 199 Md. 135, 85 A. 2d 783; Bass v. State, 182 Md. 496, 35 A. 2d 155. If the arrest was lawful, the search and seizure at the police station was proper. Robinson v. State, 200 Md. 128, 88 A. 2d 310. Evidence obtained as a result of a search and seizure incident to a lawful arrest is admissible. Kershaw v. State, supra; Robinson v. State, supra; Callahan v. State, 163 Md. 298, 162 A. 856. On the other hand, if no misdemeanor was committed in the presence of the officer, the arrest would be unlawful, a search based upon such an arrest would be unlawful and evidence thereby discovered in the possession of the accused would be inadmissible. Walker v. State, 195 Md. 412, 73 A. 2d 508. There is no dispute as to the law, and further citation of authority would be only cumulative.
There is, however, a serious dispute as to the essential fact upon which the legality of the arrest depends. That is whether or not a misdemeanor was being committed in the presence of the arresting officers, or either of them, at the time when the traverser was taken into custody at his place of business. The traverser duly objected to the admission of evidence later obtained at the police station through the search of his person on the ground *57that the arrest and hence the search were illegal. His objections were overruled and the evidence was admitted. The chief question before us is whether or not the trial court was in error on this ruling; and since the ruling was based upon a question of fact, the ultimate question with which we are confronted is whether or not this finding of fact was clearly erroneous.
The evidence that there were some papers on the appellant’s desk is clear. The testimony of Sergeant Kemple to the effect that as he came to the door of the appellant’s office and looked in he saw the appellant working on some papers and either writing, starting to write or just finishing writing something is also clear. So is his testimony with regard to the notation which he says that he saw written on one of the papers. He based his interpretation of the meaning of this notation on his expert knowledge of bookmaking operations acquired during his service as a member of the Vice Squad, and his qualifications as an expert were admitted. Such expert knowledge may be relied upon by him in viewing circumstances before him to decide whether the law is being violated in his presence. Griffin v. State, supra; Walker v. State, supra.
Code (1951), Article 27, Section 306, provides, among other things, that it is an offense “to receive, become the depository of, record or register * * * any money, bet wager, [or] thing or consideration of value, to be bet, gambled or wagered in any manner * * * upon the result of any race, contest or contingency * * (Emphasis supplied.) What Sergeant Kemple testified that he saw the defendant doing and what he testified that he saw written on the paper in front of the appellant, considered in the light of his expert knowledge of its meaning, were sufficient, if true, to show a violation of the italicized provisions of Section 306 and hence to make the arrest lawful. In this view of the matter, the fact that the mere possession of a notation of a bet, unlike the mere possession of a lottery slip, does not constitute an offense, is unimportant.
*58Thus the ultimate question is one of the credibility of a witness. The learned and experienced trial judge saw the witness and heard him testify and stated that he did not regard his testimony as “unbelievable.” Evidently, the trial judge accepted it as true, and on the basis of that testimony he held the arrest legal. The absence of any charge of violating the gambling laws when the appellant was taken into custody and when he was booked at the police station certainly lends force to the appellant’s contention that the officers did not observe any misdemeanor being committed in their presence when they were at the appellant’s office. However, even though we, with only the printed record before us, might possibly arrive at a different conclusion from that of the trial judge, yet in view of his opportunity to see and hear the witness and to appraise his truthfulness, we cannot say that he was clearly erroneous in reaching the conclusion that a misdemeanor was committed in the presence of the officer.
The appellant also urges that it was error on the part of the trial court to exclude evidence which the appellant sought to offer to show that the arresting officers had no reasonable cause to suspect that he had committed the burglary which they were investigating. Since the State abandoned any attempt to uphold the arrest on the ground that they had reasonable cause to suspect or believe the defendant guilty of a felony, this testimony was properly excluded as irrelevant to the only issue remaining in the case with regard to the validity of the arrest of the appellant.
In accordance with the views above expressed, the judgment is affirmed.
Judgment affirmed, with costs.