DNA testing confirms Travis Decker is the only suspect in the murders of his three young daughters, according to new information from investigators … as the manhunt for the fugitive continues.

The Chelan County Sheriff’s Office in Washington shared the update in the riveting case Tuesday, saying testing shows only DNA from Travis and his daughters — Paityn, 9; Evelyn, 8; and Olivia, 5 — was found on the plastic bags covering the corpses’ heads when they were discovered in a wooded area near a state campground in early June.

Police also say testing done by the Washington State Crime Lab linked Decker’s DNA profile to cable ties collected at the scene as well.

If you remember … Decker’s vehicle was discovered with bloody handprints on it near where his girls’ bodies were dumped … and police said in June they believed Decker’s DNA was a match.

It’s been nearly 3 months since the girls were reported missing and later found dead — and the manhunt continues.

The Chelan County Sheriff’s Office confirms the fugitive’s whereabouts are still unknown … and they have no evidence to suggest whether he is alive or deceased.

As we reported … tips about potential sightings were pouring in from all over the U.S. and even as far as Scotland when the case made headlines … but nothing has panned out for detectives working on the case.

Decker was in the Army and later transferred to the Washington National Guard … but Chelan County Sheriff Mike Morrison told TMZ he didn’t think his survival skills would be “anything special” compared to the trained personnel on the case.