FREDERICKSBURG, Va. (WTVR) - A 68-year-old Fredericksburg man suffering from chronic pulmonary disease says he’s not sure where he garnered the strength to fight off a double murder suspect inside his home Saturday evening.

Leonard Mara says he feared for his life, and didn’t recognize exactly who the man inside his home was at the time.

“He said ‘the cops are after me, the cops are after me,’” Mara says.

The man inside his home was John Wesley Jeffries of Fredericksburg, who is wanted in connection to the murders of an elderly couple in Fauquier County.

Police says 80-year-old Nelson Slack and his 75-year-old wife, Ethel, were found inside their home on Bunker Hill Road early Sunday after friends became worried when they didn’t show up for church.

Investigators say both victims had trauma to their upper bodies.

While police are investigating when the alleged murders took place, Leonard Mara says he’s certain it was Jeffries, 60-years-old, who confronted him outside his home on Morningside Drive around 9:30 Saturday night.

Mara says he was taking out the trash when he noticed Jeffries lurking near a shed in the backyard.

“I stopped and asked, ‘who is that?’”

Mara says the suspect approached him quickly and pushed him inside his backdoor.

“He said ‘you shut up or I will kill you right away,’” Mara recounted.

“I said ‘you cannot say that to me, come to my house and give that kind of instruction to shut up,’” Mara recalled.

Mara, a former ballroom dance instructor from Africa, said he decided to defend himself.

“That’s when I took my oxygen tank and hit him in the head!” Mara says, “and I took him and I slammed him onto the floor and sat on top of him.”

After asking for a glass of water, Mara says Jeffries went to the bathroom to clean up his bloodied forehead. That’s when Mara says he ran to a neighbor’s house for help.

“I never thought someone on oxygen could run so fast,” Mara recalled.

Investigators took blood samples and finger prints from Mara’s home on Monday morning.

Spotsylvania County investigators have been looking for Jeffries since February 16, when he allegedly tried to strangle his estranged wife inside her Fredericksburg home.

“We are currently working with Facquier County, Fredericksburg PD and the Virginia State Police to try and ascertain his whereabouts,” says Captain Jeff Pearce with the Spotsylvania Sheriff’s Department.

Jeffries was convicted in Loudoun County in 1986 of several crimes, including rape, forcible sodomy, abduction and object sexual penetration.

Jeffries is a registered sex offender with the Virginia State Police.

Police say Jeffries is considered armed and dangerous and anyone who comes in contact with him should call police immediately.

Mara said he’ll have trouble resting until Jeffries is behind bars, even though he feels confident that he can clearly defend himself.

“I don’t understand how I did it,” Mara said.