This is an appeal from the Judgment of Sentence of the Court of Common Pleas, Criminal Division, of Dauphin County, imposed at No. 499 of 1977. The procedural history and facts relevant to the issue on appeal are as follows:
On March 12, 1977, appellant visited his nephew, John Tate, and his family consisting of a wife Laura, and two children. During the afternoon and evening, appellant and John Tate visited with several of the Tates’ neighbors. *193Laura Tate related that during the evening, appellant returned alone from a neighbor’s residence and used the bathroom on the second floor. The Tates’ oldest daughter, Tanya, testified she saw appellant entice her younger sister, Lanita, from the bedroom and take her to the bathroom where he had her commit an act of fellatio upon him.
During cross-examination of Laura Tate, a Commonwealth witness, defense counsel was attempting to show that Laura was informed by her daughter of the aforementioned acts on the same night, but did not confront appellant, nor report the incident to the police until later the next day.
During the line of questioning, the following colloquy took place:
Q. You knew where Ben lived, didn’t you? You knew he lived out in Bressler?
A. Yes, but I didn’t know he was here in the city. I didn’t know he was here. I didn’t know he was out of jail, really. I didn’t know he was here until I seen him in my house. (T. 77)
Defense counsel immediately motioned the court for a mistrial which was denied. Defense counsel then refused the court’s offer of curative instructions.
Based upon the aforementioned evidence, appellant was convicted by a jury of involuntary deviate sexual intercourse. Subsequent to the denial of post-trial motions, appellant was sentenced to four to twelve years incarceration. This timely appeal followed.
Appellant contends the trial court abused its discretion in refusing the motion for a mistrial.
We note that the response of Laura Tate can not be said to have been elicited by defense counsel. Her response could only result from a strong desire on her part to convict the appellant. Such a reference to appellant being in jail served only to convey to the jury the fact that appellant had been convicted of a crime in the past. A reference to prior criminal conduct is highly prejudicial to the appellant serv*194ing to effectively strip him of the presumption of innocence. Com. v. Roman, 465 Pa. 515, 351 A.2d 214 (1976); Com. v. Groce, 452 Pa. 15, 303 A.2d 917 (1973).
The conduct of a fair trial cannot permit such testimony by a Commonwealth witness. It demonstrated her animosity towards the appellant. This is understandable as the witness was the mother of the four-year old girl involved. However, the reference to appellant’s prior criminal record is prejudicial to the presumption of innocence. Com. v. Roman (supra). We note this case is distinguishable from Com. v. Whitman, 252 Pa.Super. 66, 380 A.2d 1284 (1977) and Com. v. Cannon, 453 Pa. 389, 309 A.2d 384 (1973). The defense witnesses involved in those cases had no motive for intentionally testifying unresponsively and contra to the defendant’s interests.
The further issue to be resolved is whether or not this is the type of prejudicial testimony which could have been cured by prompt curative instructions by the court. Because of the nature of the testimonial reference, we find that curative instructions would have been inadequate. Com. v. Williams, 470 Pa. 172, 368 A.2d 249 (1977); Com. v. Fortune, 464 Pa. 367, 346 A.2d 783 (1975). The jury had to decide the issue of guilt or innocence based upon credibility. It is to be regretted that we have no choice but to find that the failure to declare a mistrial was reversible error. Com. v. McDuffie, 476 Pa. 321, 382 A.2d 1191 (1978).
Accordingly, the judgment of sentence is reversed and a new trial granted.
SPAETH, J., files a concurring opinion. MONTGOMERY, J., files a dissenting opinion.