It happened around 3:15pm in the 4200 block of Lavender at Cavalcade in northeast Houston.
Police said two cousins were moving a camper trailer. One was standing behind the trailer and the other was driving, pulling the trailer.
The driver did not realize his cousin was there and backed out, pinning him between the guardrail of another truck and the trailer.
The injured cousin -- a 65-year-old man -- was rushed to an area hospital in critical condition where he later died. His identity is pending verification by the Harris County Institute of Forensic Sciences.
Police said they consider this a tragic accident and no charges are expected.