Criminal charges have been upgraded against a Kingsport man accused of stabbing a woman last week. Poclie now confirm that Martha De La Riva has died./ Criminal charges against a man named William Clark, who is De La Riva’s son, have since been upgraded to first degree murder. Police responded to a home in the 300 block of Sequoya Drive on Wednesday. Clark had fled the scene, but was later arrested in the 4800 block of Peers Street in Sullivan County. Clark remains jailed today on a 350-thousand dollar bond.