A British aristocrat and her boyfriend have been convicted of killing their newborn daughter. Constance Marten and Mark Gordon were found guilty of gross negligence manslaughter on Monday during their second trial in London. The couple had gone on the run in early 2023, prompting a seven-week nationwide search after a placenta was discovered in their burned-out car. Police arrested them seven weeks later without the baby. The infant's decomposed body was found two days later in a garden shed. Prosecutors said the infant likely died from hypothermia or suffocation. The couple claimed it was a tragic accident.