DELPHI, Ind. (WLFI) — Monday marks 18 months since Abigail Williams and Liberty German were killed on one of Delphi's historic trails.

Investigators want people to remember that although they may not hear something new about the case every day, it doesn't mean police aren't working on it all the time.

Indiana State Police Sergeant Kim Riley said his department has one officer assigned to the investigation full time and the same goes for the FBI.

Investigators have received more than 35,000 tips to date, they have processed roughly 11-hundred of those.

The only thing they are doing differently is re-visiting some of those tips a third and fourth time. Sgt. Riley every time this case is talked about in the media or shared on social media, investigators are flooded with new leads.

Sergeant Riley said given the amount of evidence they have, it will be a long time before investigators stop calling it an active case.

"Basically when you've extinguished all of your leads all of your tips all of your information that you have gone as far as you can go with what you have that is when you're looking at a cold case, we are a long way from that," said Riley.

Sergeant Riley said there is still information investigators haven't even tapped into. He said no tip is too small and encourages people to continue sending them in and keep sharing the sketch on social media.