I contacted the ODMP admins regarding this question. They confirmed that, while their source information confirms that the murder did actually occur, there is considerable doubt as to whether Samuel L. Deputy, victim, was actually a commissioned peace officer at the time. (This event occurred at a time when there was very little stability in east Texas, in the period between the Mexican-American War and the Civil War.)
The claim that he was a Deputy Sheriff comes from US newspaper reports of the time, most of which reported the crimes from reports printed in other, more local, papers. (One even garbled the story to claim that "Mrs. Deputy" had been killed.) But at least one researcher has been unable to identify any other evidence that Samuel was a commissioned officer, and a fair amount of circumstantial evidence opposing the idea. (Beyond the lack of law enforcement bureaucracy in Orange County, Texas in 1856, there was the matter that the actual Sheriff was accused of being corrupt and backing Samuel's attackers. He wouldn't be likely to deputize someone to attack his friends.)
If Samuel was not a commissioned peace officer, this would not be the first time that the Deputy surname has been confused as someone's title in history. Suffice to say that this was a violent territorial and racial skirmish to try to assert white southern American privileges and dominance in what had previously been a mixed-race, Spanish settlement, of which Samuel was the first victim.
I received the original source information of Samuel's death from the ODMP group and updated Samuel's profile in Wikitree with that information, removing the dead references to the ODMP page.
Thanks for bringing this issue to the attention of the Wikitree community!