A mother of four was convicted Tuesday of first-degree murder for poisoning her 23-year-old Marine husband in 2002 to cash in on his $250,000 life insurance policy, part of which she used to pay for breast implants.Cynthia Sommer, 33, faces life in prison without parole when she is sentenced March 23.Sommer's attorney, Robert Udell, plans to file an appeal. Udell said an appeal was planned on two grounds: the legal sufficiency of the evidence and the fact that the judge allowed prosecutors to put on evidence of the defendant's sexual conduct with multiple partners after her husband's death.Sommer showed little reaction as Judge Peter Deddeh read the verdict.Sommer glanced briefly toward the ceiling of the San Diego courtroom, then slightly lowered her head. One of her relatives cried in the back of the packed courtroom.The verdict came on the third day of deliberations by the seven-woman, five-man jury.In addition to the murder charge, Sommer was convicted of the special circumstances of murder by poison and murder for financial gain in the death of Sgt. Todd Sommer on Feb. 18, 2002.In her closing argument Thursday, Deputy District Attorney Laura Gunn told the jury that the defendant initially did a good job of convincing everyone she was a grieving widow devastated by the loss of her husband, but her words and actions after his death reflected another reality.Sommer made four inquiries about money in the first five hours after her husband died, Gunn said.Then, over the ensuing weeks, she paid $5,400 for breast implants, had sex with four different people, hosted loud parties at her house and participated in a wet T-shirt and thong contest in Tijuana, the prosecutor said.Gunn said the defendant was the only person who could have poisoned her husband and suggested Sommer was able to get arsenic -- possibly in the bait from retail ant traps -- and give her husband a large amount of it.But defense attorney Robert Udell said there was no evidence his client poisoned her spouse or that the Marine even died from acute arsenic poisoning.He said the victim died of a heart attack, which was the finding on the original death certificate.Udell said the breast implants were an attempt by Sommer to feel better about herself after her husband's death, and if the jury thought the defendant had sex too soon after her spouse died, then she's already done time in jail for that while in pre-trial custody, he said.A test in 2003 for heavy metals showed arsenic levels more than 1,000 times the normal level in Todd Sommer's liver and 250 times above normal in his kidneys, but Udell questioned the standard operating procedures of the military laboratory that conducted the metals test.Defense experts testified at the trial that the victim should have had large amounts of arsenic present in other body parts if he was poisoned.The defendant met the victim after a failed marriage that produced three children. They were married in 1999 and had a child together.Sommer told Naval Criminal Investigative Service agents that her husband got "violently ill" on Feb. 8, 2002, 10 days before his death. She said he sought treatment, eventually recovered and went back to work but complained the night before he died that his heart was fluttering.