In the Matter of: The Appeal of the Determination of the Responsible Authority for the Department of Human Services that Certain Data about Rick McDeid are Accurate and/or Complete.

may not be cited except as provided by

Minn. Stat. § 480 A. 08, subd. 3 (1996).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C8-97-515

State of Minnesota,

Respondent,

vs.

Howard Thomas Ledden,

Appellant.

 Filed February 24, 1998

 Affirmed

 Peterson, Judge

Ramsey County District Court

File No. K196793

Hubert H. Humphrey III, Attorney General, 1400 NCL Tower, 445 Minnesota Street, St. Paul, MN 55101 (for respondent)

Susan Gaertner, Ramsey County Attorney, Mark Nathan Lystig, Assistant County Attorney, Suite 315, 50 Kellogg Boulevard West, St. Paul, MN 55102 (for respondent)

Rochelle R. Winn, Assistant Public Defender, Suite 600, 2829 University Avenue Southeast, Minneapolis, MN 55414 (for appellant)

Considered and decided by Short, Presiding Judge, Kalitowski, Judge, and Peterson, Judge.

 U N P U B L I S H E D O P I N I O N

 PETERSON, Judge

Appellant Howard Ledden was convicted of first- and second-degree criminal sexual conduct for engaging in sexual penetration with his 4-year-old stepdaughter and sexual contact with his daughter. See Minn. Stat. §§ 609.342, subd. 1(a), 609.343, subd. 1(g) (1994). He was sentenced to consecutive terms of 294 months (24 years, 6 months) and 21 months (1 year, 9 months). Ledden challenges the admission into evidence of pornographic photographs and the upward departure in sentencing. We affirm.

 FACTS

Ledden's 13-year-old daughter L.L. told her stepmother, Ann Ledden, who had just informed her that she was moving out of the house for a trial separation, that Ledden had touched her breasts that morning. Ann Ledden took L.L. to the police station, where L.L. repeated her story. That evening, M.T., Ledden's four-year-old stepdaughter, who had been left to stay with a family friend, told the friend, "I got to suck my dad's penis." The following morning, M.T. was taken to the police station, along with L.L. M.T. described acts of oral sex between her and Ledden. She also told police that she saw Ledden looking at a picture of a naked woman and a girl on the computer. L.L., who was re-interviewed when she said she had additional information, told police that Ledden had sexually abused her when she was about four or five years old, requiring her to perform oral sex on him.

Both L.L. and M.T. were interviewed at Midwest Children's Resource Center by nurse practitioner Kimberly Martinez. The girls repeated their allegations, with additional details, in the videotaped interviews, and the videotapes were played at trial. M.T., who was found competent following a competency hearing, and L.L. both testified at trial in a manner consistent with their videotaped interviews and interviews with police.

The state sought to introduce as evidence various pornographic photographs downloaded from computer diskettes that Ann Ledden had turned in to police. These diskettes were found in an unlocked file cabinet next to the home computer. The trial court denied a defense motion to suppress this evidence, but indicated before trial that it would limit the number of photographs admitted. At trial, the prosecution offered three photographs, including one photograph of a girl about the same age as M.T. performing fellatio on an adult male. The trial court ruled the photographs admissible. Ledden testified that the computer in the home was not his, and that he had only limited access to it. He testified that he had never seen the pornographic pictures, and denied ever downloading them. In closing argument defense counsel argued that the computer belonged to the family friend to whom M.T. had first reported sexual abuse.

The jury found Ledden guilty on all counts. The trial court sentenced Ledden to 294 months for the offenses against M.T., a triple departure from the presumptive sentence of 98 months. The court cited as aggravating factors the multiple forms of penetration, the repeated penetrations of M.T. over an extended period of time, the duration of the conduct, and the violation of a position of trust as the caretaker of the child. The court imposed a presumptive sentence of 21 months for the offense against L.L., to be served consecutively.

 D E C I S I O N

 I.

Ledden argues that the trial court abused its discretion in allowing the state to present three photographs showing pornographic images of children engaged in sexual acts. Rulings on the admission of evidence rest in the sound discretion of the trial court and will not be reversed absent an abuse of discretion. State v. Daniels, 361 N.W.2d 819, 828 (Minn. 1985).

Highly prejudicial material may be admissible to corroborate a victim's testimony that a defendant used or possessed the material. See, e.g., State .v Sebasky, 547 N.W.2d 93, 98-99 (Minn. App. 1996) (in prosecution for sexual abuse of boys, admission of bulletins of North American Man/Boy Love Association merely corroborated victim's testimony that he saw them in defendant's apartment), review denied (Jun. 19, 1996). The picture of a naked woman and a young girl was admissible to corroborate M.T.'s statement that Ledden showed her such a picture. The other photographs were not similar to what M.T. described, and their potential for unfair prejudice was heightened by their similarity to the charged offense. But we conclude that the admission of these photographs was at most harmless error.

The prejudicial effect of the second and third photographs is cumulative to the effect of Ledden's possessing child pornography, and especially his having shown it to a four-year-old child he was later accused of abusing. In Sebasky, this court found harmless error in admitting the contents of pedophile bulletins, based on the wealth of other pornography properly admitted. Id. at 99. Here, there was no wealth of other pornography, only one picture, but Ledden had shown that picture to his victim, unlike the bulletins in Sebasky, which were not displayed to the victims. We conclude there is no reasonable possibility that a reasonable jury might have reached a different result if the other two photographs had not been admitted. See State v. Dillon, 532 N.W.2d 558, 558 (Minn. 1995).

 II.

Ledden argues that the trial court abused its discretion in imposing a triple departure on Count I, from 98 months to 294 months. The trial court's decision to depart will not be reversed absent an abuse of discretion. State v. Lee, 494 N.W.2d 475, 482 (Minn. 1992). Severe aggravating circumstances are required to support a greater-than-double departure. See State v. Evans, 311 N.W.2d 481, 483 (Minn. 1981).

Ledden concedes that at least two of the aggravating circumstances cited by the trial court, M.T.'s vulnerability due to age and Ledden's violation of a position of trust, would support a departure of some degree. He argues, however, that multiple types of abuse and multiple incidents of abuse over a long period of time are typical of this type of offense.

This court has held that multiple penetrations alone will generally justify a double, but not a greater-than-double, departure. State v. Mesich, 396 N.W.2d 46, 52 (Minn. App. 1986), review denied (Minn. Jan. 2, 1987). Multiple types of penetration have been held to aggravate child sexual abuse offenses. State v. Casady, 392 N.W.2d 629, 635 (Minn. App. 1986), review denied (Minn. Sept. 24, 1986). Multiple incidents of abuse may be more common, but, because multiple acts was not an element of the offense charged, the trial court properly considered that Ledden committed multiple acts over an extended period of time. See, e.g., Sebasky, 547 N.W.2d at 101 (trial court in sentencing for first-degree criminal sexual conduct could rely on aggravating factor of multiple incidents, but not on violation of position of trust where significant relationship with victim was element of statute); cf. Casady, 392 N.W.2d at 635 (multiple incidents could not be used as aggravating factor because it was element of statutory offense). Based on the multiple penetrations, the violation of Ledden's position of trust, and the multiple forms of penetration, the trial court's triple departure was not an abuse of discretion.

Ledden has filed a pro se supplemental brief raising a number of issues including a claim of ineffective assistance and a challenge to the admission of the photographs. Ledden's claim of ineffective assistance is based on conclusory statements without citation to the record and on allegations for which no record exists. This court cannot determine whether trial counsel made threats to coerce a guilty plea, a claim that is irrelevant in any event because Ledden did not plead guilty. M.T.'s statement to police that Ledden showed her one of the pornographic photos provided foundation for their admission, despite Ledden's argument that he did not own the disks, a claim argued to, and presumably rejected by, the jury. Finally, this court must defer to the jury's assessment of the credibility of M.T. and L.L. State v. Daniels, 361 N.W.2d 819, 826 (Minn. 1985).

  Affirmed.