Dressed in dark clothing, the two filmed themselves as they readied to break into a local home with assault rifles and other guns, according to a new court document.

In low voices, the two discussed shooting and killing a family inside the home during the chilling 18-minute film. But passing traffic foiled their plan, the court document said.

Ludwig, who allegedly shot and killed his girlfriend Kara Borden’s parents in their Lititz home Sunday morning, and the friend then decided to continue their “night patrol” by going to the Borden home, according to the court document.

During the film, they discussed “having sex with Kara and Katelyn Borden, that the sex would constitute statutory rape and the potential to have to shoot a guy named ‘Jonathan’ if he found out about it.”

It is not clear from the court document when the film was made, or whether the pair ever did continue on to the Borden home the night the film was made.

But the friend did tell police that he and Ludwig had taken guns and gone out on several occasions on “night patrol,” with “plans of forcible entry,” according to the court document.

Ludwig, 18, of Lititz, has been charged with murdering Michael and Cathryn Borden and kidnapping their 14-year-old daughter, Kara. Police captured the pair Monday in Indiana, after Ludwig led them on a high-speed chase.

The details of the film emerged in a search warrant affidavit filed Thursday, in which police also were seeking 35 to 40 videotape cassettes kept in Ludwig’s bedroom at his 422-A W. Orange St. home.

Police discovered the film on one of Ludwig’s two laptop computers seized earlier this week.

The film shows Ludwig and a friend, Samuel Peter Lohr, 19, of Lititz, engaged in “night patrol.”

The film shows the two, dressed in dark clothing, “entering a secured room within the Ludwig home. Once Ludwig and Lohr entered this secured room, they handled various firearms that included handguns, assault type rifles and a large assortment of ammunition for these weapons,” the affidavit said.

The film then shows the two walking out of the Ludwig home with the guns and getting into a vehicle.

The two then arrived at an “unknown private residence” and talked in quiet voices about their plan to climb onto a roof and enter the home through a dormer window.

They also talked about “using their weapons to shoot and kill family members inside of the residence.”

After passing traffic “exposed the two and foiled their plan,” the affidavit said the two discussed their plans for the Borden home.

The search warrant details that police discovered a total of almost 400 other items “of evidentiary interest” stored on Ludwig’s laptop.

These other items included images of Kara Borden “in various stages of undress.”

Also, police found images of Ludwig posing with friends, family and Borden “possessing firearms, swords and what appears to be a camera cell phone taking a digital photo of himself and Kara Borden while standing in front of a mirror.”

The search warrant seeks any other computer hardware, video records, digital cameras, floppy disks, video cassettes, DVDs and other electronic items at Ludwig’s home.

Police were called to the Borden home in suburban Lititz around 8 a.m. Sunday morning after their 11-year-old son, David, fled to a neighbor’s house telling them to call 911.

His 15-year-old sister, Katelyn, fled to another neighbor’s home, later telling police she had just seen Ludwig shoot her father in the head and then heard a second shot as she hid in a bathroom.

Michael and Cathryn Borden, both 50, were found dead from a single gunshot wound to the head, police said.

Police have not said where, or if, the murder weapon has been recovered.

Outside the Borden home, by a rear door, police said on Sunday, they found what they believe was a second handgun wrapped in a red towel, brought to the scene by Ludwig.

Investigators went to Ludwig’s parents’ home and, in addition to his computer equipment, confiscated 54 guns, including shotguns, rifles and handguns that police described as three assault-type weapons, plus ammunition.

By the time police arrived at the scene on Sunday, Ludwig and Kara Borden were gone in his parents’ red Volkswagen Jetta.

Police broadcast their descriptions nationwide and by Monday afternoon, the car was spotted by Indiana State Police and the pair were taken into custody.

The teenagers were returned to Lancaster County on Tuesday. Borden was returned to her family and Ludwig was placed in county prison.

As the investigation has unfolded, friends of the young couple have said how Ludwig and Borden were having a sexual relationship and in recent weeks had become more and more withdrawn from others.

Ludwig, friends said, told them how he had been sneaking into the Borden home at night to be with his young girlfriend.

He also reportedly told a friend that he believed he could “kill someone and get away with it, disappear and nobody would find me.’’

Borden’s Web site revealed a friend’s warning that the relationship with the older teen is a “mistake,’’ and that Ludwig could go to jail.

“We couldn’t of told anyone,’’ Kara Borden replied to her friend.