DELPHI, Ind. (WLFI) — Three years after two teens were last seen alive in Delphi, Indiana State Police said they are "one piece away" from finding the killer.

ISP will not hold a news conference Thursday on the three year anniversary of when Abby Williams and Libby German went missing. That's different from the previous two years, where police gathered the media and public to provide an update.

So News 18 took our questions to Indiana's top cop.

"We are still as energized now as we were the day after," said Indiana State Police Superintendent Doug Carter.

No one questions Carter's passion to solve the Delphi double-homicide case. Every time he talks about it, you can see it in his eyes.

"It's easy to throw out the cold case idea. Nah, we're not even close to that," Carter said.

Three years after the homicides, police are continuing to keep what they know close. We asked, but Carter couldn't answer many of our specific questions on the investigation. However, he is renewing that police are on the heels of the killer.

"One piece away, one piece away," Carter said when asked how close they were to solving the case. "Eventually, somebody will do the right thing. It might be the killer himself; might be a person who knows who he is."

Related: ISP release video, additional audio and a new sketch of the subject

Two investigators still work full-time on the case from the Delphi City Building. The ISP Laboratory Division, intelligence team and Fusion Center are still combing through the now 50,000 tips.

"We never throw anything out," said Carter. "When we are done with all we have, we start over. I think I got 18 tips yesterday. Just me at my desk."

It's easy to be your own detective and criticize the actual ones, but Carter says they accept that pressure.

"I'm so proud of them. I'm so proud of them," Carter said. "We can't talk about what we think. Everybody else can. Or what they believe happened. We can't. There has been some criticism of me, and I'm willing to take that. I can't explain all the things that I know."

Just police and the killer have that knowledge.

"He has no idea what we know, but one day he will," Carter added.

This a different type of case, because police have almost everything they need 'heroically' captured on Libby German's cellphone.

"I can't think of a time in my entire career, or in many other careers, where we have the voice of the person we believe is the killer, a photograph of who we believe is connected to the murder, and even a snip-it of how he moves," said Carter.

Indiana State Police have released a new video, sketch and audio of who they believe killed Abigail Williams and Liberty German in Delphi on Feb. 13, 2017. Read all the new information released here: https://t.co/WAQy2GPOYO pic.twitter.com/sbNXiHdnkN — WLFI News 18 (@WLFI) April 22, 2019

Carter said more information could be released in the future, but for now, this is what we are getting. He thinks it's enough.

"Somebody knows," Carter repeated. "Somebody knows."

He wants you to remember the two sketches are not photographs.

"I believe that eventually, we are going to be able to say this person's the killer, and there's a combination of those two images that will land on his face, whatever that might look like," Carter explained.

Carter said this is one of his priorities in life. Even if it takes another year or more, he's going to get it done for the families.

"If we hit year four, I hope we are sitting here again," said Carter. "But we will do everything within our power, and within the parameters of law, to find the individual who did this to Abby and Libby."

A memorial service is being planned at Delphi United Methodist Church Thursday from 5 to 7 p.m. They're taking donations for food and pet supplies.

If you know anything in the killings of Abigail Williams and Liberty German, send your tip in. Email abbyandlibbytip@cacoshrf.com with any information.

For our complete coverage of the Delphi Homicides from the past three years, click here.