The reward for missing autistic New York City teen Avonte Oquendo has been raised to $70,000 as local celebrities join the search and the lawyer for the 14-year-old’s family attempts to find out how the mute student was able to leave his Long Island City school without supervision.

Avonte went missing Oct. 4, when he was seen walking out of the Center Boulevard School in the Long Island City section of Queens. Authorities have no clues as to Avonte’s whereabouts, but the NYPD is focusing its search around train yards and train tunnels because the autistic teen has a fascination with trains.

Oquendo family attorney David Perecman filed a notice of claim -- the first step to filing a lawsuit -- against the city and the school system alleging that the parties should have supervised the 14-year-old. Avonte, who is nonverbal, requires constant supervision at his school.

PIX 11 is reporting that Avonte’s father, Daniel Oquendo, is optimistic that his son will be found alive despite the 14-year-old being missing for more than a week. The New York City television station reported that local hip-hop celebrity Ralph McDaniels has assisted in the search for Avonte.

The NYPD shares that optimism, according to NBC New York. Police said more than 80 tips have been amassed on Avonte’s whereabouts, although there’s no sign of the autistic teen.

"We're still pretty optimistic and hopeful that we will find Avonte and deliver him back home to his family," NYPD Chief of Detectives Phillip Banks told a news conference on Saturday. "We've done an extensive search; that search entails aviation units using the best technology we possess.”

Autism advocacy group Autism Speaks said the reward for Avonte’s safe return has been raised to $70,000. The reward is being offered by Perecman’s firm, the employer of Avonte’s mother, Autism Speak co-founders Suzanne and Bob Wright, Manhattan law firm Mayerson & Associates, the nonprofit autism school Manhattan Children’s Center, and an anonymous donor.

“All of us at MCC are praying for Avonte’s safe return and hope that these additional funds might enhance the public awareness about the search for Avonte,” said Manhattan Children’s Center co-founder Thomas Gelb.

Autism Speaks said it is common for autistic children to wander around and noted that the behavior is “dangerous and puts tremendous stress on families.”