delivered the opinion of the court:
The prime issues: modus operandi and identification.
Do they permit evidence of other offenses committed by the defendant?
We hold in the affirmative.
Terry Sievers was charged by information with the September 21,1975, rape of Terri Lee Scott in Champaign, Illinois. He was convicted by a jury and sentenced to serve 5 to 15 years’ imprisonment.
*882Under a subsequent information Sievers was charged with the November 30,1975, armed robbery and armed violence of Marcia Elble. After another jury trial, he was convicted and sentenced to 5 to 15 years in prison for armed robbery, to run consecutively to his prior rape sentence.
(On our own motion these cases have been consolidated for opinion as our cases numbered 14196 and 14097, respectively.)
RAPE CASE. At the first trial, Terri Lee Scott (age 16) testified that on the Sunday morning of September 21, 1975, she was visiting friends in Champaign and was out walking in search of a grocery store. On several occasions she noticed a blue Chevy Nova following her. As she approached the IGA store, she observed the Nova park in the store’s parking lot. A man she recognized as the driver of the car then approached her, grabbed her by the arm, drew a knife and pulled her away from the street toward an adjoining cornfield. In a grassy area between the field and the street he threw her down, sat on her and held his hand over her mouth to muffle her screams. The man ripped off her clothes and fondled her breasts and crotch. The man forcibly had intercourse with the prosecutrix for about 30 seconds. He then got up and told her to walk south while he walked north towards the IGA.
Miss Scott started south but turned and headed toward the IGA when she heard the man’s car leave. At the store, she called the police, made a complaint, and gave a description of her attacker. While scanning a group of photos during her second trip to the police station, she identified Sievers as the man who raped her.
ARMED ROBBERY CASE. Marcia Elble, a University of Illinois student, testified at the second trial that she was attacked on Sunday, November 30,1975, shortly after 11 a.m., while walking between Weston Hall and Gamer Hall dormitories. A man came up behind her, grabbed her arm, stuck a sharp object in her back, and told her it was a holdup. She was then backed up against the Gamer cafeteria doors and faced the man as he held a knife to her ribs. After giving him *9, Elble pushed the man and tried to get away. The man grabbed her once again, said he wanted her body, put his hand up her skirt, and told her if she cooperated it would not be so hard. Elble pushed him again and ran toward the intramural building. There she reported the attack and was taken by the police to the police station where she drew a sketch of her attacker.
In both cases the trial court admitted testimony concerning attacks on other University of Illinois students expressly for consideration on the issue of defendant’s identification and design. Sievers asserts this testimony was erroneously admitted because the character of these assaults was not sufficiently similar to the offense against the complainants to establish modus operandi.
Although evidence of extra-indictment offenses is not generally *883admissible, evidence of other crimes which goes to show motive, intent, identity or modus operandi is an exception. (People v. McDonald (1975), 62 Ill. 2d 448, 343 N.E.2d 489; People v. Palmer (1970), 47 Ill. 2d 289, 265 N.E.2d 627.) In McDonald our supreme court found there was no error in admitting a prosecution witness’ testimony that she had experienced an attack similar to the one encountered by the complainant. Similarities in the two attacks in McDonald included the early morning time, the entrance gained by removing a window screen and standing on an overturned refuse basket, the manner of attack upon a female victim, and the intruder’s apparel of gym shoes, khaki pants, and gloves.
In all four attacks allowed into evidence in the rape case before us, the assailant was a tall, thin young man with long blonde hair. He approached the young female victim on foot while they were walking down a sidewalk and began the sexual assault by fondling or attempting to fondle the victim. Similarities between the attack on the Scott girl and two of the other attacks are that the attacks occurred on a Sunday morning and the attacker used a knife.
In addition to the similarities shared by all four attacks, the attack in our armed robbery case and the two other attacks allowed into evidence all involved a robbery preceding a sexual assault, an attacker announcing his sexual intent, and attacks occurring on the University campus during a two-week span. Similarities between the attack on Miss Elble and one of the two other attacks are that the attacker wore a blue down-filled jacket, the attacker used a knife, and the attack occurred on Sunday morning.
Since “peculiar and distinctive features” are common to the attacks, the trial court did not abuse its discretion in admitting the testimony on the issue of identification and design. (People v. Therriault (1976), 42 Ill. App. 3d 876, 356 N.E.2d 999.) The testimony was also proper in view of the holding of People v. Dewey (1969), 42 Ill. 2d 148, 246 N.E.2d 232, and People v. Cole (1963), 29 Ill. 2d 501, 194 N.E.2d 269, that evidence of other offenses is admissible if relevant for any purpose other than to show a propensity to commit a crime.
Sievers’ alibi defense in both cases raised the identity issue. In the rape case Sievers contended that he was not in Champaign the morning of September 21 because he had been hunting near Hugo with his wife and Dennis and Carla Vail at the time Miss Scott was raped. Defendant’s story was corroborated at the trial by his wife, Dianne, and Dennis and Carla Vail.
At the armed robbery trial Sievers claimed he was also hunting on the day of the November 30 attack. His wife testified that she had gone hunting with him, and his mother stated he was in bed when she left her home at 9 a.m. and that she saw him when she got home at 12 noon. At the second trial, defense counsel extensively questioned defendant and *884another witness concerning the discrepancy between Sievers’ hazel or brown eyes and the blue eyes of their attacker that the witnesses reported to the police. Since the defendant’s identity was in issue, evidence of other crimes — whose characteristics yielded a distinct and unique combination when considered together and viewed in toto — was properly introduced to establish this element.
Sievers’ counsel also objected to the introduction into evidence of the knife that was in Sievers’ possession at the time of his arrest. In People v. Ostrand (1966), 35 Ill. 2d 520, 221 N.E.2d 499, overruled on other grounds in People v. Brocey (1972), 51 Ill. 2d 514, 283 N.E.2d 685, the court ruled that where there is evidence indicating that an accused possessed a weapon at the time of the offense, a similar weapon found in his possession at time of arrest may be admitted against him. An identification of the weapon as the one actually used in the commission of the offense is unnecessary. Likewise, the court in People v. Longstreet (1974), 23 Ill. App. 3d 874, 320 N.E.2d 529, admitted an automatic pistol and a large bore revolver in addition to the snub-nosed blue-steel small bore revolver identified by the victim as the robbery weapon. Therefore, even though the present victims stated that the knife used was different than the one found in Sievers’ possession this testimony only affects the probative value and not the admissibility of the similar weapon into evidence.
Defendant next claims the trial court erred in the armed robbery case in allowing evidence that Dianne Sievers had attempted to smuggle hacksaw blades to her husband while he was in jail. The record indicates, however, that this testimony was admitted to show bias and interest on the part of the witness. It would seem clear that a witness may be impeached in a criminal case by showing bias or interest in the outcome of the trial because it is pertinent to the credibility of that witness. (People v. Sawyer (1971), 48 Ill. 2d 127, 268 N.E.2d 689; People v. Henson (1975), 32 Ill. App. 3d 717, 336 N.E.2d 264.) Since the record clearly reflects that this was the precise reason that the testimony was admitted here, there was no error.
Sievers further claims that in the second trial the court abused its discretion in imposing consecutive sentences because he had no prior criminal record. First of all, it is hornbook law that the imposition of consecutive sentences is within the trial court’s discretion. (People v. Ledferd (1968), 94 Ill. App. 2d 74, 236 N.E.2d 19; People v. Sykes (1973), 10 Ill. App. 3d 657, 295 N.E.2d 323.) And a trial court may properly impose a consecutive sentence if the nature and circumstances of the offense — and the history and character of the defendant — warrants such a sentence to protect the public from further criminal conduct by the defendant. (Ill. Rev. Stat. 1975, ch. 38, par. 1005—8—4(b).) In reaching *885his decision that a consecutive sentence was necessary to protect the public, the trial judge below discussed the statutory factors and obviously considered the facts of the case. Sievers had robbed his victim at knifepoint in the daytime and demonstrated by word and action his sexual intentions. He had been convicted of a rape committed under similar circumstances approximately two months before the armed robbery offense. Since there is substantial basis in the record supporting the trial court’s judgment that a consecutive sentence was necessary for the public’s protection, we find no abuse of discretion.
Sievers next contends that his convictions must be reversed because he was not charged by indictment and did not waive his right to be so charged. This argument is unpersuasive since a defendant has no right to be charged by indictment rather than by information, as we held in People v. Tibbs (1977), 46 Ill. App. 3d 310, 360 N.E.2d 993. We considered this issue in depth in Tibbs and rejected the argument. We again subscribe to our position as enunciated in Tibbs.
Defendant’s final claim is also without merit. He contends that section 111—2(a) of the Code of Criminal Procedure of 1963 (Ill. Rev. Stat. 1975, ch. 38, par. 111—2(a)) is unconstitutional since it fails to set forth intelligible standards to guide the application of legislative authority. The court in People v. Vaughn (1977), 49 Ill. App. 3d 37, 363 N.E.2d 879—which we cited with approval in People v. Ferguson (1977), 54 Ill. App. 3d 886, 368 N.E.2d 170—noted that the powers exercised by a state’s attorney are executive powers. Consequently, there is no invalid delegation of legislative authority in permitting a state’s attorney to select the vehicle of prosecution.
For these reasons, we affirm the lower court in both cases.
TRAPP, J., concurs.