TACOMA, Wash. -- A human jaw bone uncovered by a developer on a residential construction site sparked a much larger excavation and surprising find for Renton police.

Police received a phone call Tuesday from a developer after they discovered the human bone at a site located at 2211 Edmonds Ave. NE in Renton.

The medical examiner’s office believed the bone was buried for an extended period of time, so Renton police scheduled an excavation of the site.

After the state's archeological and historical preservation department excavated the site Thursday, the deeper they dug, the more evidence they found of human bones, teeth and even metal parts of ancient coffins dating back to 1901.

Police said the cemetery may go back as far as 110 years.

“The city was incorporated in 1901 but, I know that a lot of records were probably kept on note pads back in those days," said Renton’s mayor, Denis Law.

Under a new state law, the site is now regarded as an official historic burial plot. Building here has to stop, and the state law forces the developer to hire an archeologist to find the rest of the remains.

The builder must preserve the burial plot or pay to have the remains moved to a real cemetery, according to the new law that doesn’t officially start until July 1.

The site is next to a brand new duplex that would have been in move-in condition in June.

Nothing will happen here until state officials meet with the builder next week.