summary of intruder theory efforts by Colorado Bureau of Investigation

(CNN)It's been 25 years since the murder of 6-year-old JonBenet Ramsey riveted the nation, and now Boulder, Colorado, investigators say they have analyzed almost 1,000 DNA samples to find the killer.

It is the latest in a string of numbers that reveal their ongoing efforts:

Police have received, reviewed or investigated more than 21,000 tips, letters and emails.
Detectives have traveled to 19 states.
They have interviewed more than 1,000 people.
They have processed more than 1,500 pieces of evidence.

In a statement marking the 25th anniversary of the murder, Boulder police said they actively "use new technology to enhance the investigation" and check regularly for DNA matches in order to solve this case.
"Thanks to the huge advances in DNA technology, multiple suspects have been run through the system to check for matches. CBI (Colorado Bureau of Investigation) has updated over 750 reference samples with the latest DNA technology. The Boulder Police Department works closely with CBI on future DNA advancements.

has updated over 750 reference samples with the latest DNA technology.

Additionally, there were additional samples of male DNA on the garrote, with six different examples found belonging to unknown individuals. With the crime scene open to anyone in the initial stages, it's likely some came through police failings. However, the same DNA from the underwear was found elsewhere around the body. It was under the fingernails, under the waistband of the victim's leggings, on the wrist bindings and on the garrote.