Two 18-year-old men are under arrest and police will present their case for possible charges on Friday, a police representative said at a news conference.
The suspects will be identified at that time.
23-year-old Megan Boken was fatally shot Saturday in her car at an intersection in St. Louis while in town for a volleyball reunion game.
Police did not go into specifics, but did say they believe robbery was the motive.
The suspects were captured with the assistance of the community and witnesses, according to investigators.
The victim's father, Paul Boken, released a statement Thursday night saying the family is "gratified with the progress in the case and with the efforts of the St Louis Police Department." He also thanked the people who came forward to assist with the case.
The arrests came on the same day that funeral services were held for Boken in Wheaton.
"She was everything, she was one of my best friends, she was always happy, always in a great mood, always willing to help me out. She'll be missed dearly," David Bruckner said outside the funeral home.
A $31,000 reward was posted for information leading to an arrest in the case.
St. Louis Police were investigating Boken's death as a "probable attempted robbery" since there's no evidence Boken knew the suspect. Witnesses told police they saw a man arguing with Boken before firing shots into the car.