Bucks County District Attorney Matthew D. Weintraub said this afternoon that police are making progress in their search for four young men who have been missing since last week, but that there is much investigative work remaining.

"We're going to solve this," Weintraub told reporters at an afternoon briefing in Solebury Township, noting that at least five municipal police departments, the Bucks County Detectives, Pennsylvania State Police and the FBI are involved in the investigation.

"We are making great progress, but there's so much more work to do," said Weintraub, who has described the investigation as an "all hands on deck" effort.

Throughout the day, investigators searched multiple locations for clues to the whereabouts of the men, one of whom went missing last Wednesday and the others on Friday. Calling the case "very serious and very sensitive," Weintraub asked the public for "your patience and your prayers for these four young men."

Missing since Wednesday is Jimi Tara Patrick, 19, of Newtown Township. Missing since Friday are Mark Sturgis, 22, of Pennsburg, Montgomery County; Dean Finocchiaro, 19, of Middletown Township, and Tom Meo, 21, of Plumstead Township.

Although there are indications that some or all of the men knew one another, investigators are working to confirm that information and the extent of any connections, Weintraub said.

When asked by reporters whether foul play was suspected in the disappearances, Weintraub responded, "It sure would seem so," based on "information that I know but can't share at this time."

Weintraub addressed the media not far from the location of one search, a sprawling rural property along the 6000 block of Route 202 in Solebury. “Obviously it has investigative relevance,” he said of the property.

Municipal police from Newtown, Middletown, Solebury, Buckingham and Plumstead Townships are involved in the investigation, along with county detectives, state police and the FBI, Weintraub said.

He urged anyone who has information about the men’s whereabouts at any time since their disappearance to call 215-297-8201, or to click the "Submit a Tip" tab on this page. He said the young men's families are anxious, but remain hopeful that they will be found.

Persons leaving tips on Crimewatch may do so anonymously if they so choose.

Weintraub said he plans to give the media another update on the investigation at 11 a.m. Tuesday in Solebury.