There are two towns in Texas named Lewisville, one is in Denton Co, the other is in Waller Co.
But, the TX Dth Idx shows he died in Tarrant Co, TX
Lessard, Norman L., d 15 Apr 1993 Tarrant Co, TX.
Now, Denton Co, is next to Tarrant Co. Could be Norman was in a hospital in say Ft Worth and died there. Death Certificate will be recorded in the county where he died, but obit probably published where he lived.
You might try RAOGK (Random Acts of Genealogical Kindness) site. There are several volunteers listed for Denton Co, TX, most for taking photos in cemeteries, some will do vital records, but a couple of them specifically say they will do obits.