Eric Johnson had a problem.

His new girlfriend was supposed to come to town last week, but his old flame was still in the mix, sharing a home with him in Port Richmond.

With little compassion, cops said, Johnson, 36, came up with a cold-hearted solution: he brutally killed his live-in girlfriend, Jean Jackson, and went to extreme lengths to make sure she would never be identified.

When a group of kids discovered Jackson's body in a vacant wooded area near train tracks on Saturday, her head was covered in a pillowcase and a plastic bag, and a wool scarf was tied at her neck, cops said.

Her collarbone and both of her legs were broken. All of her ribs were crushed. There were clear "attempts to mutilate her face and grotesque attempts to mask her identity," said Chief Inspector Joe Fox, head of detectives.

In spite of the gory efforts, Fox said detectives discovered a plethora of evidence to connect Johnson to the murder of Jackson, a Haverhill, Mass., native.

After taking him to police headquarters yesterday morning for questioning, cops charged Johnson with murder, abuse of a corpse and related offenses.

Fox said Johnson, who had family ties in Philadelphia, left the area in 1993. He spent the next 12 years in Massachusetts and became "well known to police in Massachusetts," Fox said. "He has a violent, criminal past."

In 2005, Johnson met Jackson, 40, in Lawrence, Mass. They became "live-in partners," Fox said. Johnson's mother died in Philadelphia, prompting him to move back here with his live-in love last September.

Homicide Sgt. Anthony McFadden said Johnson met his new girlfriend through a phone-chat service. "They developed some type of relationship," McFadden said, and late last Thursday, Johnson picked up his new love at the Center City Greyhound bus station.

By then, McFadden said, Johnson had allegedly killed Jackson. The motive was "a domestic issue between him and [Jackson]. Having a new girlfriend, trying to get her out of the way," he said.

Autopsy results revealed that "some kind of object was used to beat her," McFadden said, including multiple times to the face.

McFadden said evidence gathered by police clearly shows that the murder occurred in Jackson's home on Clearfield Street near Emerald. "The physical evidence is overwhelming," he said.

Detectives believe that Johnson later dumped his girlfriend's body in the wooded area behind Witte Street near Clearfield, just a few blocks from his home.

Fox said detectives are concerned about Johnson's ability to lure women through phone-chat services, given his violent history, and plan to link up with Massachusetts state police to see if Johnson could be tied to other crimes involving women.

Investigators also are trying to track down Jackson's family. "We don't even know if she has any family locally," Fox said. *