Opinion by
Mr. Justice Jones,On September 30, 1953, appellant entered a plea of guilty to murder generally. Found guilty of first degree murder by a court en banc, he was sentenced to life imprisonment. There was no motion for a new trial and no appeal from the original sentence. Seven *561years later appellant filed a petition for writ of habeas corpus which was denied on the narrow ground that habeas corpus cannot be employed as a substitute for an appeal. E.g., Com,, ex rel. Johnson v. Myers, 402 Pa. 451, 167 A. 2d 295 (1961), cert. denied, 366 U.S. 921 (1961). On appeal we similarly affirmed the denial of relief on this procedural point. Com. ex rel. Sampson v. Banmiller, 406 Pa. 147, 176 A. 2d 430 (1962). In 1968, appellant sought relief under the provisions of the Post Conviction Hearing Act, Act of January 25, 1966, P. L. (1965) 1580, §1 et seq., 19 P.S. §1180-1 et seq. (Supp. 1971), by alleging, inter alia, a violation of Douglas v. California, 372 U.S. 352 (1963). Following an evidentiary hearing, appellant was granted leave to file post-trial motions as though timely filed. These motions were filed, argued and denied; this appeal followed.
The evidence presented at the degree-of-guilt hearing reveals that appellant and two co-defendants conspired to rob a taxicab. Although there is some dispute, the evidence overwhelmingly demonstrates appellant’s knowledge of the fact that one of his accomplices was armed with an automatic pistol. The three conspirators then engaged a taxicab, with appellant and another seated in the back seat while the actual slayer sat on the passenger’s side in the front seat. After the cab driver had driven several miles, the “triggerman” brandished his weapon and ordered the cab driver to stop. Seconds later the cab driver was fatally wounded. Although appellant was not the actual killer, each individual was charged with murder under the felony murder rule.
In our view, appellant’s principal contention is that his guilty plea was unintelligently entered since it was accompanied by testimony establishing a complete defense and should have been rejected. Despite an evi*562dentiary conflict, there is substantial evidence, if believed, that both appellant and his fellow conspirators in the back seat fled the cab immediately after the actual assailant ordered the cab driver to halt; appellant was allegedly thirty-five to fifty feet from the taxicab when he heard the shot. Before any examination of his testimony, we must first decide whether any exculpatory evidence would vitiate the guilty plea.
In North Carolina v. Alford, 400 U.S. 25 (1970), the Supreme Court was faced with the issue whether a guilty plea may be accepted when accompanied by the accused’s testimony that he had not shot the victim. This question was answered in the affirmative: “while most pleas of guilty consist of both a waiver of trial and an express admission of guilt, the latter element is not a constitutional requisite to the imposition of criminal penalty. An individual accused of crime may voluntarily, knowingly, and understandingly consent to the imposition of a prison sentence even if he is unwilling or unable to admit his participation in the acts constituting the crime.” 400 U.S. at 37. We had reached the same conclusion almost two years earlier in Com. v. Cottrell, 433 Pa. 177, 249 A. 2d 294 (1969). However, this language must be read in conjunction with Com. v. Roundtree, 440 Pa. 199, 202, 269 A. 2d 709, 711 (1970): “We think it is logical and correct that if a defendant pleads guilty to a criminal charge, and in the next breath controvenes the plea by asserting facts which, if true, would establish that he is not guilty, then his guilty plea is of no effect and should be rejected. For on its face, such a situation would show that the plea was not entered with a complete comprehension of the impact. [Citations omitted.] In other words, a defendant should not be allowed to plead ‘guilty’ from one side of his mouth and ‘not guilty’ from the other.”
*563From these cases it is readly apparent that a guilty plea coupled solely with a flat denial of responsibility is entirely separate and distinct from a guilty plea accompanied by an assertion of facts establishing an affirmative defense; in the latter situation, it is error to accept the guilty plea. Owing to appellant’s exculpatory evidence, this appeal properly fits within the Roundtree rationale. As in Roundtree, our next level of inquiry devolves upon an examination of the facts asserted by appellant and whether they constitute a valid defense.
By a host of opinions it is well established that if a homicide occurs in the furtherance of a robbery, all who participated, including those physically absent from the scene of the crime, are equally responsible provided that the homicide was committed by the defendant or an accomplice acting in furtherance of the felonious undertaking. E.g., Com. v. Williams, 443 Pa. 85, 277 A. 2d 781 (1971) ; Com. ex rel. Smith v. Myers, 438 Pa. 218, 261 A. 2d 550 (1970) ; Com. v. Batley, 436 Pa. 377, 260 A. 2d 793 (1970). On the other hand, this Court has held that although there is a conspiracy to commit robbery, one of the conspirators will have a valid defense to a murder charge if the accomplice voluntarily abandons the scheme appreciably before the homicide occurs, giving his fellow conspirators sufficient time to follow his example. Com. v. Doris, 287 Pa. 547, 135 A. 313 (1926). See also, 40 Am. Jur. 2d Homicide, §§40, 125 (1968); 40 C.J.S. Homicide §9(e)(3) (1944); 1 Wharton’s Criminal Law and Procedure §110 (1957). We are of the opinion that appellant’s testimony does not meet the criteria of this defense and that the court below properly accepted appellant’s guilty plea.
Accepting appellant’s testimony, there is no doubt that appellant, unlike Frank Doris, voluntarily with*564drew from the common design. However, appellant’s testimony demonstrates his abandonment was well nigh simultaneous with the fatal shot. He did not leave the taxicab until the “triggerman” revealed the pistol and ordered the cab driver to stop. Considering appellant’s distance of thirty-five to fifty feet from the taxicab at the time of the shot, his abrupt departure from the taxicab preceded the shot by scant seconds. Although appellant’s co-felon in the back seat joined appellant’s exit, there is no assertion that any communication was relayed to the actual killer other than appellant’s departure. “The guilt of one engaging in an unlawful enterprise consists in part in the encouragement and support that he gives to those who commit the crime; and the influence and effect of such encouragement continue until he withdraws the encouragement by acts or words showing that he disapproves or opposes the contemplated crime. He cannot escape responsibility merely by the expedient of running away.” 40 Am. Jur. 2d Homicide §40 (1968).
Appellant next contends that his plea of guilty was not knowingly and intelligently entered. Certain facts are stressed in support of this contention: (1) he was sixteen years of age at the time of trial with a reduced intellect;* (2) appellant’s mother and his counsel essentially made the decision to plead guilty rather than appellant and (3) the plea was unintelligently entered as counsel led appellant to believe his guilty plea could be withdrawn if there was merit to his defense of withdrawal. From our examination of the record, we are not persuaded by the first and second points. See, e.g., Com. v. Moore, 440 Pa. 86, 90-91, 270 A. 2d 200, 203 *565(1970). In light of our earlier conclusion that appellant could not successfully invoice the defense of withdrawal, trial counsel correctly viewed appellant’s exit as a possible mitigating factor rather than a complete defense. Accordingly, the facts surrounding appellant’s departure were fully presented to the court below. Had the defense of withdrawal been established on these facts, the court below would have erred, under Bound-tree, by not ordering a withdrawal of the plea. We are of the opinion that appellant’s guilty plea was intelligently made.
Since it is well settled that evidence of good character is admissible in a murder trial and is to be regarded as evidence of a substantive fact like any other evidence tending to establish innocence, e.g., Com. v. Aston, 227 Pa. 106, 75 Atl. 1017 (1910), appellant contends the trial court erred when it rebuffed counsel’s attempt to introduce character and reputation testimony prior to the adjudication of guilt; this evidence was subsequently received for sentencing purposes. In light of the reason for this rule of evidence—the defendant in a criminal case is permitted to prove his good character in order to negative his participation in the acts charged, I Wigmore on Evidence, §55 (3d ed. 1940)—one can seriously question the relevance of such evidence following a guilty plea to an indictment charging felony-murder. Despite the burden placed on the Commonwealth to prove all the elements of first degree murder after a guilty plea to murder generally, e.g., Com. ex rel. Kerekes v. Maroney, 423 Pa. 337, 223 A. 2d 699 (1966), a guilty plea in a felony-murder case normally removes the issue of participation; the other issues that the Commonwealth must prove, such as whether the homicide occurred in furtherance of the felony, are unaffected by evidence of the accused’s good character where the accused is not the actual slayer. *566In any event, coupled with, counsel’s failure to object to the court’s delayed receipt of appellant’s character evidence, we are of the opinion that the trial court did not commit any fundamental error.
Lastly, appellant contends his trial counsel was ineffective for three reasons: (1) counsel failed to move for a withdrawal of the guilty plea and assert the defense of withdrawal; (2) counsel failed to correct the court’s mistaken impression that appellant was seventeen years of age at the time of the offense whereas appellant was one month short of sixteen; and (3) counsel unrealistically emphasized the charges of the death penalty. The first argument has been fully treated earlier and the second is insignificant. The third contention may be persuasive in the proper case; however, this element was but one factor in counsel’s trial strategy. Viewing counsel’s principal objective to obtain a lesser conviction even though the Commonwealth proceeded on a theory of felony-murder, cf., Com. v. Hoffman, 439 Pa. 348, 266 A. 2d 726 (1970), we are of the opinion that, “the particular course chosen by counsel had some reasonable basis designed to effectuate his client’s interests”. Com. ex rel. Washington v. Maroney, 427 Pa. 599, 604, 235 A. 2d 349, 352 (1967).
Judgment of sentence affirmed.
Mr. Justice Eagen concurs in the result.
Mr. Justice Cohen took no part in the decision of this case.
School reports dated four years before the homicide indicated appellant’s “mentality placed him at the lower end” and that he had an Intelligence Quotient of 65. There is no direct evidence of his intelligence at. the time of trial.