Some statistical info, hard to decipher with regard to this case: And oddly, seems the only thing I could find with multiple attackers is from the mid-90s:
Offender Characteristics
In single-offender rape/sexual assault victimizations, Whites and Blacks were victimized most often by members of their own race (Whites by Whites, 78.4%; Blacks by Blacks, 83.5%).
Of the 39,989 multiple-offender rape/sexual assault victimizations in 1994, 84.8% involved only male offenders, and 6.8% involved male and female offenders.
Female-only offenders were involved in 8.4% of victimizations.
Almost half of all multiple-offender rape/sexual assault victimizations had no age-of-offender distinction (44.8%), another 24% were committed by 12-20 year olds, and 15.2% by 21-29 year olds. Only 5.9% of those committed were by offenders 30 years of age and older. The age of 10.2% of victimizations by multiple-offenders was not known.
Forty-eight percent of all rapes/sexual assaults in 1994 were committed by an offender perceived to be under the influence of drugs or alcohol, 27.9% were perceived to be not on drugs or alcohol, and in 23.9% of the incidents the use of drugs or alcohol was not known or could not be ascertained.
Half of all multiple-offender rape/sexual assault victimizations (49.4%) were committed by Whites, 29.5% by Blacks, 15.5% by mixed races, and 5.7% by other races than White or Black. Rates were not provided to allow for comparisons among the races.
Of the multiple-offender rape/sexual assault victimizations, 76% were committed by strangers.
http://www.nmcsap.org/statistics.html#cd