Fujita was spotted driving shirtless, with his car windows down and music blaring.
He also called a cousin later that night, explaining to prosecutors, "I just wanted to get my mind off of it."
When Astley didn't return home from her job at a clothing boutique the night of July 3, it was her father who filed a missing person's report with the Wayland Police Department.
Police questioned Fujita shortly afterward. He said Astley had visited their home around 7:45 p.m. then left after they spoke briefly while she remained in her car.
Police later searched Fujita's home, where he lives with his parents. They found blood in the garage and on an exterior door handle, and traces of blood on the kitchen floor, kitchen sink and bathroom sink.
They found a pair of blood-spattered sneakers in an attic crawlspace above Fujita's room.
Police also discovered a plastic garbage bag filled with bloody water-logged clothing, including a sweatshirt with pockets containing dirt similar to that of the marshland where Astley's body had been found.
Fujita had been planning to attend Trinity College in Connecticut this fall.
Astley, who also recently graduated from Wayland High School, had been accepted to Elon University in North Carolina. Her father told the Boston Globe Astley was their only child, and said she was a former captain of the high school tennis team who sang in her school's a capella group and wanted to work in the fashion industry.
Fujita doesn't have a previous criminal record, and there is no indication that Fujita had abused Astley while they were dating, District Attorney spokeswoman Jessica Venezia Pastore said.