BAKERSFIELD, Calif. (KGET) — Forty-four search warrants have been served, 83 people interviewed and 170 items seized in the investigation into the disappearance of two California City toddlers, Bakersfield police said Tuesday.

Police tweeted an image with statistics regarding the investigation and said the department is continuing to work with the California City Police Department as well as the FBI and the National Center for Missing & Exploited Children to discover what happened to Orrin and Orson West.

“This is not a cold case,” the tweet says in part.

Orrin, 4, and Orson, 3, went missing Dec. 21. The boys’ adoptive father, Trezell West, has said the children were playing outside as he gathered firewood. He said he briefly went back inside the house, and when he came out the boys were gone.

Police say 16 “mass area” searches have been conducted, investigators have searched three locations outside the state and more than 200 tips have been followed up. Data is continuing to be extracted from cellular and electronic devices, and seized items are being forensically examined.

All family members connected to the boys have been interviewed, according to police.

Anyone with information regarding their disappearance is asked to call 661-327-7111, the National Center for Missing & Exploited Children at 1-800-THE-LOST or Kern Secret Witness at 661-322-4040.