Two Marquette University students serving as Milwaukee Police Department interns played a part in the investigation that led to the arrest of a man some have called “The North Side Strangler.”

Early Saturday morning, authorities arrested Walter Earl Ellis — the man police say may have killed nine women over a 21-year period. At this time, Ellis is only being charged with two of the murders. More charges are expected to be filed.

According to Milwaukee Police Chief Edward Flynn, the arrest was made possible through the efforts of several different agencies.

“Good police work and good police science have led us to Walter Ellis,” Flynn said at a press conference Monday.

Most notably, the MPD’s Cold Case Unit of the Homicide Task Force was able to connect tips, clues and evidence that led them to Ellis.

Julie Knyszek and Jennifer Cossyleon, who were assigned to the unit as interns, are two Marquette seniors who worked closely with detectives to solve the case.

Knyszek said her position with MPD required her to take all 195 tips collected throughout the investigation and enter them into a software program provided by the FBI. Utilizing this software allowed Knyszek and the Cold Case Unit to link different tips to different suspects, helping narrow down Ellis’ identity. She also reviewed old homicide files, pulling out important details from each murder.

Knyszek helped create a DNA database for investigators to use when linking DNA found at the scene to samples of DNA collected from suspects. In the end, this was one of the most important tools in solving the murders. Ellis was linked to the murders by a DNA sample collected from him during the execution of a search warrant on Aug. 29.

The student internships with the Cold Case Unit started in May, and were scheduled to end on Aug. 11. But due to advancements made on the case and the students’ success, MPD allowed Knyszek and Cossyleon to stay.

The interns were one part of a larger team that helped find Ellis. The FBI created a criminal profile of the suspect using evidence that MPD collected and sent to FBI profilers in Quantico, Va. An agent from the FBI’s Eau Claire office served as a liaison to MPD, according to Leonard Peace, public affairs specialist for the FBI in Milwaukee.

An arrest warrant was issued after the State Crime Laboratory linked Ellis’ DNA to evidence found at the scene of nine homicides.

Ellis was apprehended Saturday when a Franklin police officer noticed his car. MPD was notified and Ellis was taken into custody.

Now that Ellis has been arrested, the district attorney’s office is preparing for trial. The length of the trial, however, remains unclear.

According to Marquette University Law School Professor Janine Geske, an expert on trial processes, extensive trials typically last three to four weeks. However, Geske believes the length of Ellis’ trial may differ depending on his type of defense.

Ellis is currently being held on $1 million bond.