DELPHI, Ind. -- "Today is the day."
That's the common phrase for investigators working on finding out who killed Delphi teenagers Abigail Williams and Liberty German last month.
Indiana State Police Sgt. John Perrine said on Thursday they are remaining positive despite the fact that one month has gone by without an arrest for anybody in connection with the deaths.
"Not 'Today might be the day,'" he said. "Today is the day. They're optimistic. I've never seen a coordinated effort the way I've seen right now."
There are more than 25 police agencies and hundreds of officers involved in the search.
"We are very optimistic that we are going to find a resolve(sic) to this case," Perrine said.
Libby's grandfather, Mike Patty, addressed the public for the first time since the girls' murders on Thursday.
Patty urged everyone to take just "one minute" to review the evidence that has been released. He said every tip is important and each one will be considered by investigators.
"They don't just go into a bucket," said Patty. "We are confident that together we can bring justice to those responsible for this horrible crime."
The families of both girls recently toured the investigation headquarters in Delphi.
While there, Abigail's grandparents made a stop at a board where the community can leave messages for investigators . Their message to police offered prayers and thanks:
FULL DELPHI COVERAGE | Indiana's 'Singing Contractors' record emotional tribute to Delphi murder victims | ISP: Do not use social media to report tips on murders of Delphi teens | Don't share the Delphi suspect 'sketches' | FBI moves to larger space for Delphi case | Delphi girls murdered: What is the evidence? | New audio could help solve Delphi killings | Delphi murders have parents watching kids closer | Report Delphi tips to police, not social media | Security concerns on Delphi trails after murders | Don’t share the Delphi suspect ‘sketches’ | German family friend: ‘She was a good kid’ | See somebody walking near Delphi? Call police | Prosecutor: Don’t harass people about Delphi | ISP on Delphi murders: "Everyone is a suspect" | PHOTOS: Motorcycle fundraiser for families of Delphi murder victims | Search warrant served at Delphi home in connection to teen murders, no arrests made | Friend of killed Delphi girl: ‘I question everything’ | State Police say an Amber Alert would not have done ‘any good’ | A look at the property where the bodies of two missing teen girls were found | ISP wants to speak to this man and anyone who was near Delphi trail when two teens went missing | Community in shock after bodies of two missing teens found | Community concerned about safety as police search for suspect in death of teens | MAP: Where the two bodies of the teen girls were found near Delphi, Indiana | Why wasn’t an Amber Alert issued when girls were reported missing in Carroll County? | Delphi Timeline: Teen girls found dead after disappearing while hiking | Two bodies found during search for Carroll County teens | MISSING: Two 13-year-old girls dropped off to go hiking near Carroll County trail