
263 S.E.2d 608 (1980)
STATE of North Carolina
v.
Thomas FULTON, Jr.
No. 99.
Supreme Court of North Carolina.
March 5, 1980.
*609 Rufus L. Edmisten, Atty. Gen. by William W. Melvin, Deputy Atty. Gen., Raleigh, for the State.
*610 Larry G. Reavis, Winston-Salem, for defendant-appellant.
HUSKINS, Justice:
The court permitted Officer Everhart, over objection, to state his opinion that the tread design shown in the photograph of the shoe tracks which were found near the Family Grocery and the tread design on the bottom of defendant's tennis shoes were identical. This constitutes his first assignment of error.
Officer Everhart was not qualified as an expert witness in the field of latent evidence identification. He was, however, a trained police officer who had participated in the investigation of the armed robbery of Family Grocery and was the officer who found the shoe tracks in the field behind the store. Even so, we are discussing opinion evidence of a non-expert witness.
Ordinarily, opinion evidence of a non-expert witness is inadmissible because it tends to invade the province of the jury. "The essential question in determining the admissibility of opinion evidence is whether the witness, through study and experience, has acquired such skill that he is better qualified than the jury to form an opinion as to the subject matter to which his testimony applies." State v. Phifer, 290 N.C. 203, 225 S.E.2d 786 (1976), cert. denied, 429 U.S. 1123, 97 S.Ct. 1160, 51 L.Ed.2d 573 (1977). Accord, State v. Mitchell, 283 N.C. 462, 196 S.E.2d 736 (1973). Whether a witness has the requisite skill to qualify him as an expert is, nothing else appearing, a question within the exclusive province of the trial judge. State v. Combs, 200 N.C. 671, 158 S.E. 252 (1931).
Here, no effort was made to qualify Officer Everhart. It follows, therefore, that his opinion was inadmissible because the jury was apparently as well qualified as the witness to draw the inferences and conclusions from the facts that Officer Everhart expressed in his opinion. Wood v. Insurance Company, 243 N.C. 158, 90 S.E.2d 310 (1955); State v. Cuthrell, 233 N.C. 274, 63 S.E.2d 549 (1951).
Although the trial court erred in permitting Officer Everhart to express his opinion that "the design on the dirt and the design on the bottom of the tennis shoes were the same," we are of the opinion that defendant was not prejudiced by the error because the State offered expert testimony through S.B.I. Agent Layton that the shoe tracks near the crime scene and the track design on defendant's tennis shoes were similar. Agent Layton said, "it is my opinion that the sole impression or track design on the base of State's Exhibit No. 11 (defendant's tennis shoes) is consistent with the shoe track impression represented on State's Exhibits 8(a), 8(b) and 8(c)." These latter exhibits are photos of shoe tracks in the field near the Family Grocery operated by Mr. Agha. We hold that admission of Officer Everhart's opinion testimony was harmless error beyond a reasonable doubt.
Defendant further complains in his first assignment of error that the court erred in permitting Officer Everhart to testify that defendant's Chrysler could have been drifted downhill to the new location where the officer found it "even without power steering and brakes." Defendant contends this constitutes impermissible opinion testimony. We find no merit in this contention. The officer had previously testified that he had entered the vehicle when he first discovered it, had started the motor and moved the vehicle backward and forward. At that time the vehicle was parked on an incline. Thus, the officer had personal knowledge that the vehicle was not completely disabled and any driver could permit it to drift down the incline without power steering or power brakes. Hence, it is more accurate to say that the officer was giving a shorthand statement of facts within his own knowledge rather than expressing his opinion. Defendant's first assignment of error is overruled.
Laura J. Ward, a member of the S.B.I. and an expert in the field of forensic serology, testified that examination of defendant's tennis shoes revealed the presence of human blood; that the blood type of Mr. Agha was group A, PGM type 1 and Hp *611 type 2-1; that the blood on defendant's tennis shoes was group A, PGM 1, Hp 2-1. The witness then explained her answer as follows: "There are numerous blood groups or blood group systems present in the blood. The ABO system is the one that is most commonly recognized. You can be either a Group A, Group B, Group O, or Group AB. However, there are numerous other blood group systems present that are also genetically controlled, just as your ABO factors are, and two of the systems that were analyzed in this particular case are the PGM system, and PGM stands for phosphoglucomutase, and the other system is haptoglobin. Within the PGM system you can be basically one of three types: you can by PGM 1, PGM 2, or PGM 2-1. Within the haptoglobin system [Hp], you can be basically one of three types, Haptoglobin 1, Haptoglobin 2, or Haptoglobin 2-1."
Over objection, this witness was then permitted to say: "The combination of these blood groups occurs in approximately 11% of the United States' population." Defendant assigns admission of this statement as error, contends it has no relevancy and that the only effect of allowing the 11% figure into evidence "was to incite prejudice in the minds of the jury." Defendant argues that a city the size of Winston-Salem would contain thousands of persons with the same blood type as the victim in this case, and the challenged evidence could only mislead the jury into believing that the particular blood type allegedly found on defendant's shoes came from an extremely limited source when in fact the source actually encompassed a very large number of people. We see no error here.
Justice Exum, speaking for the Court in State v. Gray, 292 N.C. 270, 233 S.E.2d 905 (1977), said: "We believe the better view to be that the results of blood grouping tests are generally admissible. While their positive probative value is somewhat tenuous, we see little, if any, ascertainable prejudice which could arise from their admission. As we observed in State v. Johnson, [280 N.C. 281, 185 S.E.2d 698 (1972)]: `At most, analysis of hair and blood samples tended to identify the defendant as belonging to the class to which the guilty party belonged. The analysis might have indicated he did not belong to that class.' Obviously the tests are highly probative negatively." So it is here. Had the blood grouping test shown that the blood on defendant's tennis shoes did not belong to the same group as Mr. Agha's blood, this would have been highly significant in defendant's favor and would tend to exonerate him. On the other hand, since the blood test showed that the victim's blood group was the same as the blood on defendant's shoes, the test was relevant but weakly probative in character because 11% of the population has the same blood type as Mr. Agha. In a city the size of Winston-Salem, this 11% would encompass several thousand people whose blood could have been on defendant's shoes. The challenged statement is therefore mildly unfavorable to defendant but essentially harmless because its probative value is so minute. Certainly no prejudice resulted. Exclusion of the challenged testimony would not have changed the result of the trial. This assignment is overruled.
Finally, defendant contends the court erred in allowing testimony concerning the blood tests because a proper chain of custody showing continuous possession of defendant's tennis shoes was not established. Thus, defendant says, the integrity of the blood test evidence was destroyed. This constitutes his third and final assignment of error.
The record shows that S.B.I. Agent Layton on 20 February 1979 received defendant's tennis shoes through the mails from Officer Everhart for footprint comparisons. Agent Layton kept the shoes in his control, custody and possession while they were in the S.B.I. laboratory and until they were returned to Officer Everhart by mail on 21 February 1979.
On 10 April 1979, S.B.I. Agent Laura J. Ward received by mail from Officer Everhart defendant's tennis shoes for analysis as to blood stains on them. Agent Ward testified: "I did keep that package and those shoes in my custody and control and possession *612 while doing the examination and until I mailed them back to Officer Everhart."
Defendant asserts two prejudicial breaks in the chain of custody during the time Agent Layton had possession of the shoes. Defendant first argues that after Agent Layton received the shoes in the mail on 20 February 1979, he left them unattended for an hour in his unlocked private office. Agent Layton did not remain continuously in his office during that hour. Secondly, defendant asserts that someone other than Agent Layton carried the package to a mail pickup point after Layton had examined the shoes and made the footprint comparisons.
There is no merit in defendant's final assignment of error. The possibility that defendant's tennis shoes (State's Exhibit 11) could have been stolen, or other shoes substituted for them, while S.B.I. Agent Layton's private office was temporarily unlocked or while the shoes were carried to a mail pickup point by some employee of the S.B.I. laboratory other than Agent Layton, is too remote to break the chain of custody and too tenuous to render the blood test evidence incompetent. Compare State v. Hunt, 297 N.C. 258, 254 S.E.2d 591 (1979). We think the evidence supports the conclusion that the chain of custody of State's Exhibit 11 was unbroken. Immediately upon receiving the shoes on 20 February 1979, Agent Layton marked them with his initials, the date of receipt, and S.B.I. file number. Within an hour after receiving the shoes he examined them and then placed them in a locked file cabinet until he got ready to dictate the case. The shoes were repackaged and mailed to Officer Everhart the next day. Agent Layton testified without reservation that the markings on the shoes were his and that the shoes marked State's Exhibit 11 were the same shoes he had received and the same shoes he had sent out. There is no evidence that the shoes, at any time, had been tampered with. Accordingly, defendant's third assignment of error is overruled.
Defendant received a fair trial free from prejudicial error. The judgments appealed from must therefore be upheld.
NO ERROR.
