PHOENIX -- (KNXV) -- The boyfriend of missing Phoenix woman Christine Mustafa pleaded not guilty in connection to her disappearance on Tuesday morning.
On June 8, Phoenix police arrested 37-year-old Robert Interval on one count of first-degree murder.
Mustafa was last seen by a colleague as she was leaving work on May 10. Her sister was the last person to hear from her later on that day.
Interval reportedly told police that Mustafa had walked to work on the morning she didn't show up for her scheduled shift the following day.
Mustafa's body has yet to be located.
Interval's next court appearance is scheduled for August 8.
Phoenix Police released the following timeline on Mustafa's disappearance:
May 10, 2017: Christine was last seen by a coworker as she was leaving work.
May 10, 2017: Later in the day, Christine spoke to her sister by telephone. This was the last time Christine had been heard from.
May 11, 2017: Christine failed to show for her scheduled work shift.
May 11, 2017: The family of Christine called Phoenix Police and asked them to check the on the welfare of Christine. The police went to her home but there was no answer at the door. Christine's boyfriend arrived while police were at the home and he told them Christine had left for work earlier that morning on foot. Phoenix Police entered a Missing Person report at this time.
May 16, 2017: Detectives from the Phoenix Police Department served a search warrant on Christine's home in an effort to locate clues to her disappearance.
June 8, 2017: Mustafa's boyfriend arrested, booked for first-degree murder