Prosecutors in Ellis County on Monday announced the penalty for 39-year-old Phillip Wayne Waller of Maypearl.
A jury in Waxahachie convicted Waller of indecency with a child over the October 2010 incident. He received the maximum penalty Nov. 9.
The victim's father testified he briefly left his older boy in the toy section of a Walmart in Midlothian while taking his 4-year-old son to the bathroom. The father says he returned to find Waller was pressed up against the victim.
Midlothian police say Waller fled but was chased by store employees, who turned in a description of his car. Waller was later arrested.
