Jason Smith, the exterminator who said he was wrongly arrested and coerced into a confession, was found guilty Wednesday of strangling pediatrician Melissa Ketunuti and setting her body on fire. He was immediately sentenced to life in prison without parole.

Smith, 39, who spent almost three hours testifying in his defense, was almost speechless after the Philadelphia Common Pleas Court jury convicted him of murder, arson, risking a catastrophe, abuse of corpse, and a weapons charge.

When Judge Sandy L.V. Byrd asked the Levittown man whether he had anything to say before sentencing, Smith's voice crackled with emotion: "No, your honor."

Byrd also imposed consecutive prison terms totaling 17 to 34 years on the other charges.

Defense attorney J. Michael Farrell said Smith would appeal.

The guilty verdicts, announced three hours after the jury of six women and six men began deliberating, drew gasps and tears from Ketunuti's surrogate family - the parents of her Amherst College roommate, who "adopted" her after she emigrated from Thailand for college.

Across the courtroom sat Smith's mother, Sharon, alone, hands clasped, as she had been daily since the trial began May 4.

It was only when court adjourned and deputies led Smith away that his mother began crying. She declined comment.

Smith was arrested two days after the Jan. 21, 2013, slaying of Ketunuti, 35, a physician and researcher at Children's Hospital of Philadelphia.

Smith met Ketunuti the day she died when he went to her home in the 1700 block of Naudain Street to get rid of mice. He was arrested after police discovered his number on Ketunuti's cellphone and surveillance video showed him in the area of her home before and after she was killed.

Smith confessed after five hours of interrogation, telling detectives he and Ketunuti had argued about the quality of his work. He said he became enraged, strangled her, and set her body on fire to cover up the crime.

Farrell's efforts to mount a false-confession defense were undermined when Assistant District Attorneys Jennifer Selber and Peter Lim played four recordings of Smith's prison phone calls with his girlfriend, the mother of his then-4-year-old daughter.

The couple - apparently oblivious to notices that their calls were being recorded - joked about trial strategy and discussed the difficulty the defense would face convincing a jury that he was mentally impaired enough to falsely confess.

Ketunuti's slaying and the way her body was bound and set afire mobilized her friends and colleagues.

They also attended the trial daily and kept in touch with Ketunuti's ailing parents in Thailand.

On Wednesday, they eulogized Ketunuti with victim-impact statements that appeared to touch the judge and lawyers.

Pamela Rock, Ketunuti's college roommate, spoke of how the doctor "touched the world in so many ways" and wanted to "help the less fortunate abroad." Ketunuti was specializing in infectious childhood diseases in the Third World.

Rock's mother, Wendy Diamond, spoke for Ketunuti's mother, a Belgian native, about the loss of her only child.

"She did not want to come because she would be unable to control her emotions," Diamond said. "Her grief is overwhelming."

Diamond's husband, Kenneth, spoke for Ketunuti's father, overcome with grief and ailing from diabetes.

"This was indeed a senseless killing," Byrd told them, "and from what I heard during the course of this trial, the world has lost someone who had much to give."

jslobodzian@phillynews.com

215-854-2985 @joeslobo