CENTREVILLE — It's been six months since someone killed 11-year-old Jodi Parrack. The girl's mother found her body in a cemetery in St. Joseph County, Mich. No one has been arrested for the crime, but Thursday investigators announced they have a promising new lead.

Police and the prosecutor’s office held a press conference Thursday afternoon. They announced they’ve found what they’re calling new “scientific forensic” evidence, though they will not confirm if it is DNA evidence.

All prosecutors and investigators would say is that this new evidence won't do them any good unless they have a suspect to compare it with.

Thursday marks the six-month anniversary of Jodi's death, and prosecutor Doug Fisher said the news conference was intended as a "progress report" of the investigation.

By the numbers, it has been staggering: 664 tips, more than 700 people interviewed, even calls from psychics offering help.

To date, three quarters of those leads have been closed, but police confirmed Thursday they still have 75 active "suspects," but no one they'll call a "person of interest."

Meanwhile, three investigators continue to work on this case full time, but many questions remain unanswered. And despite what they called “unprecedented cooperation," and this new lead, it's clear that frustration is only growing.

"We have had 100 percent cooperation from the family of the victim — Jodi’s parents and her entire family — they have all helped in the gathering of that scientific forensic information and everyone who has helped us with that scientific forensic information has been cleared," Fisher said.

Frustration was clear in the prosecutor's voice Thursday. Still, he left the news conference with an emphatic promise: “We will find out who committed this crime.”

But he again asked for the public's help, particularly in letting them know of anyone who moved away from the Constantine area between early November and the end of December.