Two men serving life sentences for the home-invasion slaying of a Montgomery County woman were charged today with the 2006 slaying of a Bucks County man.

On Nov. 15, 2006, Jarrett Osborne, 18, was fatally shot in the buttocks while fleeing two armed robbers in the Winder Village section of Bristol Township.

Two months later, Kelly Carter-Hernandez, 39, was shot point-blank in the throat and killed while resisting two robbers who had forced their way inside her West Pottsgrove home.

Now, after ballistics and DNA tests allegedly linked one gun to both crimes, authorities say two of the six people convicted of murdering Carter-Hernandez also killed Osborne.

In both cases, authorities say, the robbers believed - mistakenly - that the victims had large sums of drug cash.

Charged today with first-degree murder in Osborne's death was David Ramtahal, 24. He already is serving life in state prison after pleading guilty to first-degree murder in the Montgomery County slaying.

Authorities say Ramtahal was the shooter in both cases.

His alleged accomplice, Nyako Pippen, 20, was charged with third-degree murder. Pippen, convicted of second-degree murder in the Carter-Hernandez slaying, is serving life in the Montgomery County prison.

Both men also face charges of robbery, conspiracy, and possessing an instrument of crime.

The Bucks County case was taken before a grand jury because some witnesses were reluctant to testify, District Attorney Michelle Henry said.

According to the grand jury presentment, Osborne had been standing with his brother and cousin at Winder Drive and Elmhurst Avenue when Ramtahal and Pippen drove by and assumed the three to be drug dealers.

Both got out of the car wearing masks and wielding guns, the presentment said. When Pippen cocked his shotgun, Osborne turned and ran, and Ramtahal shot him, authorities say.

"We have no evidence that [Osborne] was dealing drugs," Henry said. "In fact, he was working in a retirement community at the time."

Bleeding heavily from his wound, Osborne lost consciousness en route to Frankford Hospital-Torresdale and died shortly after arriving.

Carter-Hernandez, a guard at a nuclear power plant, had been living with a convicted criminal who was the apparent target of her killers. As her two daughters listened downstairs, she had struggled with Ramtahal before he shot her in a second-floor room.

After her slaying, Montgomery County authorities recovered a 9mm handgun that matched the casing of the bullet that had killed Osborne. DNA lifted from a ski mask found near the site of the Bristol slaying and from the handgun also were a match for Ramtahal.

He already had given investigators a leg up by accidentally dropping his cell phone in Carter-Hernandez's home. Several calls had been made from the phone to Pippen shortly before the slaying.

Osborne's slaying had been one of six unsolved shooting deaths in the same area of Bristol Township between April 2006 and the end of last year. Bristol Township Police Lt. Chick McGuigan would not say whether the arrests in Osborne's death might help crack the other cases.

"They're all obviously under investigation, and we're putting a tremendous amount of time and attention into them," Henry said. "This is one, and we hope to resolve the other ones."

Contact staff writer Larry King at 215-345-0446 or lking@phillynews.com.