DNA report reveals match in Christa Worthington murder trial

BARNSTABLE - A string of numbers on a piece of paper - the keystone in the prosecution's case in the Christa Worthington murder trial - was finally introduced into evidence yesterday.

After days of gruesome murder scene evidence and testimony from a wide-ranging cast of witnesses, DNA linking Christopher McCowen to the former fashion writer's corpse was shown to jurors by Assistant District Attorney Robert Welsh III before court broke for the weekend.

A swab taken from Worthington's right breast after her stabbing death revealed DNA from McCowen, according to Christine Lemire, a part-time supervisor at the Massachusetts State Police Crime Lab. Lemire testified about 23 samples of DNA she tested from Worthington's body and evidence at the scene, as well as 49 DNA samples gathered from other individuals.

Lemire said there is an extremely high level of statistical certainty that DNA found on Worthington's corpse came from McCowen. She said the genetic material collected from Worthington's right breast that matches McCowen's DNA could occur only once in 199.8 billion African-Americans.

After DNA from a sample of material collected at a crime scene is processed, analysts generate a series of numbers that characterize a person's genetic profile, Lemire said. ''It's a blueprint for our very identities,'' she said.

A small amount of Worthington's own DNA was also mixed in with the sample from her breast. But swabs from other areas of her body also revealed possible matches with McCowen, Lemire testified.

A vaginal sample showed mostly Worthington's DNA, but also a potential so-called ''minor'' match for McCowen. That means that less of his DNA than Worthington's was found in the sample, but his was still a one-in-1.1 billion match.

Neither of those two swabs contained any DNA from Jeremy Frazier, who McCowen said fatally stabbed Worthington through the lung.

DNA collected from Worthington's fingernails was less conclusive, but still showed a possible link to McCowen, Lemire said. Underneath a fingernail on her right hand, analysts found DNA from Worthington and her infant daughter, Ava, who was possibly trying to nurse when her mother's body was discovered.

Some of Ava's DNA was found on her mother's left breast, which would have been consistent with a toddler's attempts to nurse, Lemire testified.

But genetic material from at least three other men, possibly including McCowen, was also found in the fingernail clipping.

Welsh tried to show that DNA from other men could have come from casual contact - a handshake, a pat on a bare shoulder - but Judge Gary Nickerson allowed Lemire to testify only about the results of the testing, not about how the DNA could have been deposited on Worthington's body.

Semen stains found on a brown blanket at the crime scene also were subjected to DNA testing. A paramedic has testified he covered Worthington's half-naked corpse with the blanket for the sake of ''decency.''

Semen taken from the blanket matched DNA from Tim Arnold, the former live-in boyfriend who discovered Worthington's body and was once a prime suspect in her murder.

Lemire testified the semen could have been on the blanket long before the slaying. Some DNA can last as long as 20 or 30 years, she said.

Under cross-examination by defense attorney Robert George, Lemire said Worthington's fingernail clipping was never compared to Arnold's DNA, and a blood stain on the heel of her left clog is from an unknown source.

The trial continues Monday morning in Barnstable Superior Court. Closing arguments could begin as early as Thursday, according to Nickerson.