Denise Murter did not believe in UFOs until she saw one above her Falls Township home in April of 2008.

It all started when her Yorkie woke her up in the middle of the night.

"My dog was growling like somebody was in the house," she said. “I got up and searched. I found nothing.”

A few minutes later, she took her dog out back. When she looked up, the middle-aged woman saw a “huge round dome.” The dome featured blue and green lights.

In the following days, Murter reported the incident to UFO investigators who took samples of a substance left behind on the ground after the encounter. The substance turned out to be made of the elements boron and magnesium.

Murter, an employee at the Lower Bucks YMCA, said she believes she saw an alien spacecraft in 2008.

Murter and about 350 other believers ventured to a UFO Conference hosted by Mutual UFO Network (MUFON) at the Bucks County Sheraton in the Langhorne section of Middletown Township over the weekend.

The conference, billed the largest on the East Coast, featured about a dozen speakers and took place Friday, Saturday and Sunday.

Alex Sunday drove with a friend from Asbury Park, N.J. to attend the weekend conference.

Sunday said he became interested in the study of UFOs after he saw something strange fly over his girlfriend’s Staten Island apartment when he was a young man.

“I first came on a lark,” he said. “I come now with a healthy dose of skepticism.”

Richard Dolan, an author and historian, spoke at the event about his research on government documents that cover the subject of UFOs.

“They’re likely not little green men, but there is something strange that our national security apparatus is concerned about,” Dolan said.

Alleged UFO abductee, Travis Walton spoke to conference-goers about his 1975 experience.

Walton called people who doubt the existence of UFOs “closed minded.”

The decision to hold the meetup in Bucks County was based on the rash of UFO sightings that swept Lower Bucks County, including the Oxford Valley area, in 2008, organizer John Ventre said.

Ventre and MUFON investigators flocked to the area in the wake of the sightings and began investigations.

In close to 80 percent of UFO reports, investigators can determine the cause of the sightings, Ventre said. Most of the sightings are caused by manmade objects in space or astronomical conditions.

In Bucks County, MUFON team members could only explain about 70 percent of what people saw. That figure gives the sightings some credit, Ventre, a retired UPS security and public affairs director from Western Pennsylvania, told Patch.

MUFON will hold a similar conference in Pittsburgh in a few weeks and expects to come back to Bucks County next year.

Do you believe in UFOs? Did you see anything strange over the skies of Levittown? Tell us in the comment section below.