Billings Police Chief Rich St. John said Friday that solving a series of home-invasion sexual assaults and robberies against young women in recent months is the Police Department's "highest priority."
Speaking at a City Hall news conference, St. John said two detectives have been assigned full time to investigate the case.
The department is being assisted by the Yellowstone County Sheriff's Office, the Yellowstone County Attorney's Office and the FBI, he said.
"Citizens should know that this case is our highest priority and we have dedicated a significant amount of resources to work it full time," St. John said.
Police are investigating six similar crimes that began Jan. 9 and continued through Tuesday. In four of the cases, an armed man entered the home of a young woman and sexually assaulted and robbed her.
Two incidents were thwarted attempts, St. John said. He did not provide details.
The assaults have occurred between the hours of 2 a.m. and about 6 a.m. in an area west of Virginia Lane, east of 32nd Street West, north of King Avenue West and south of Rimrock Road.
The crimes have happened roughly a month or a month and a half apart, and toward the middle or end of the month. There was a two-month period without incidents.
The assailant is described as a white man between the ages of 25 and 35, less than 6 feet tall with a slender build and weighing less than 200 pounds.
Detectives continue to work on developing a better description of the assailant, St. John said, and are canvassing the areas where the crimes occurred. None of the victims could provide further details about their attacker, St. John said.
All of the victims have been women in their 20s with similar hair color and living in similar residential situations. The assailant, who used a weapon, entered the victim's residence through unsecured doors or windows.
The victims suffered minor injuries, but St. John declined to elaborate on the extent of the injuries or what was taken during the robberies.
The first reports of the assaults became public in early June when Montana State University Billings police issued a warning for students to take extra precautions because college-age women appeared to be targeted by the assailant.
St. John said Friday that two of the six victims were MSUB students, and the college is required by federal law to report such incidents when they occur on campus or involve students.
St. John said other details of the case are being withheld from the public to protect the investigation. But he asked that anyone with information that may help solve the crimes to call the Police Department or Crimestoppers at 245-6660.
The police chief also said that it is possible more assaults have occurred and have not been reported. He said about 80 percent of sexual assaults go unreported.
"We want to make sure there are no other victims," St. John said. "We want to make sure they are cared for and the crime investigated, and elicit additional information, if any."
St. John reiterated steps people can take to protect themselves:
— Always lock doors and windows, even when you are home.
— Make note of unfamiliar people or vehicles in your neighborhood.
— Do not provide personal information to people you don't know.
— Do not post personal information on social media websites.