A man accused of stabbing his wife to death after she received roses from a Philadelphia sportscaster pleaded guilty to third-degree murder today.

The man, Raymond Stumpf, 54, who was known locally as Mr. Telemart for his cable television home-shopping program, could be sent to prison for up to 24 years when he is sentenced on Sept. 29.

Mr. Stumpf was accused of nearly decapitating his wife, Marlene, 47, with a kitchen knife at their home in Pottstown, a suburb of Philadelphia, on Jan. 20 when he learned that another man had sent her a dozen roses. The other man turned out to be a radio and television sportscaster, Howard Eskin.

Mrs. Stumpf had corresponded with Mr. Eskin over the Internet. Mr. Eskin denied they were romantically involved, and said the roses were meant to cheer her up.