Thousands of people have signed an online petition seeking an independent investigation into how Morgan Hill police handled the investigation into the disappearance and murder of Marissa DiNapoli.

The petition on Change.org is addressed to the City of Morgan Hill, Santa Clara County officials, and the California Department of Justice, asking for an investigation and audit of the Morgan Hill Police Department's response. It had more than 8,500 signatures as of Thursday afternoon.

The 18-year-old DiNapoli was found dead on July 2 under a bridge near Anderson Lake after she had gone missing the previous weekend. At that time, she was seen on a surveillance camera with 20-year-old Martin Mendoza, with whom family members said she had a turbulent and abusive relationship.

Mendoza was arrested on July 6 at the California-Mexico border crossing in Calexico after entering the U.S. from Mexicali and was charged with her murder. At his arraignment on Tuesday, prosecutors said DiNapoli had been stabbed multiple times in the back.

The petition launched by DiNapoli's siblings claims the Police Department failed to respond with urgency in the early hours of her disappearance, saying that the day after she was reported missing, her sister provided police with Mendoza's exact location.

According to the petition, officers confronted Mendoza in person but did not detain him for questioning. Mendoza fled within hours of the encounter with police, the petition claims. Police had indicated Mendoza had not been cooperative with the investigation; he was later named as a person of interest, and the department appealed to the public for help in finding him.

The department's inaction cost DiNapoli a chance at being rescued, risked the safety of Morgan Hill community members, and violated the public's trust, according to the petition.

"We believe this inaction was not only unacceptable — it was dangerous," the petition stated. "We believe that racial and systemic bias played a role in the failure to act."

On Tuesday, the Morgan Hill Police Department gave the following statement to KSBW 8:

"We can't imagine what Marissa's entire family is going through. This loss is, in a word, unimaginable, and we continue to wrap our arms around Marissa's entire family and stand ready to help provide them with whatever services or support they may need.

"We do want to address some of the concerning comments that have been generated online. Unfortunately, we have been made aware that some of these come from a small faction of Marissa's extended family members.

"Again, first and foremost, this is about Marissa. Justice for Marissa. We remain committed to keeping focus on the man who murdered Marissa, and we recognize our responsibility to ensure that correct and accurate information is shared with our entire community who have gone above and beyond to support Marissa's family, including through body-worn camera footage that highlights how dedicated our department was from the moment we received a call from Marissa's father that she was missing. While we cannot share that footage now, as the case is in the DA's hands, it will be made available as soon as we are able.

"To our community, please help us as we carry this investigation forward and work with the District Attorney's Office to ensure Marissa's death is not in vain. Help us ensure that we all follow what was asked of us by Marissa's family: respect their desire for privacy to grieve, and their wish that no one profits from this tragedy by generating online solicitations.

"We will make no further comments on the rumors being spread about the investigation, and we encourage our community to rally behind Marissa's father, while the police department remains focused on the man who committed this heinous crime."

Mendoza is currently being held without bail and is scheduled to enter a plea on September 9.