(KIWA) — The O’Brien County Sheriff’s Office was among the agencies that helped investigate a federal case resulting in two men receiving a combined 45 years in prison.
Forty-eight-year-old Floyd Clifford Coates Jr., also known as Cliff Coates, and 60-year-old Dennis Lawson of Whiting were sentenced last week in Sioux City. The former brothers-in-law were convicted following an 11-day jury trial in November 2025.
Coates was convicted of six counts, including drug trafficking, unlawful possession of firearms and obstruction of justice. He was acquitted of two additional obstruction charges involving allegations that he threatened witnesses.
Lawson was convicted of one obstruction-of-justice charge for threatening a witness. He was acquitted of drug-trafficking and other obstruction charges.
Trial Evidence Detailed 2019 Disappearance
Evidence presented at trial showed Coates was part of an organization that transported pounds of methamphetamine from Colorado to Iowa during the spring of 2019. Prosecutors said he also possessed firearms to protect the operation.
During Easter weekend that year, Coates arranged a drug resupply trip to Kansas City, Missouri. He asked an Iowa woman to drive from Sioux City to Blair, Nebraska, and then take him to Kansas City.
Coates arrived in Blair with 18-year-old Sunny Sramek of Nebraska. Sramek had told friends and family she was taking a day trip to Omaha with Coates and did not mention Kansas City.
When the Sioux City driver arrived, she saw Sramek motionless inside the Ford Explorer in which Coates and Sramek had traveled. The driver testified that Sramek appeared to have overdosed and that Coates told her he had given Sramek methamphetamine.
Coates abandoned the Kansas City trip and directed the woman to Lawson’s home near Whiting along the Missouri River. The driver testified that Coates and Lawson disappeared for a time after arriving. When they returned, Sramek’s body was gone.
The woman said she and Coates then cleaned the vehicle. She testified that Lawson threatened her by saying that if she told anyone, “it would be her funeral.”
Forensic Evidence Contradicted Coates’ Account
Coates later told several people that Sramek had overdosed. While awaiting trial, prosecutors say he told cellmates that he had killed Sramek after raping her.
In both accounts, Coates allegedly said he threw Sramek’s body into the Missouri River to conceal evidence. He told one person, “no body, no case.”
Forensic testing of the Explorer found Sramek’s DNA and evidence suggesting she had struggled inside the vehicle. An FBI geologist testified that a window had been broken from inside by three blunt-force impacts consistent with someone kicking it.
A medical examiner said the apparent convulsions were consistent with someone dying from a methamphetamine overdose. Prosecutors also said Coates’ account of his movements was contradicted by cellphone location information and other evidence.
Sentences Handed Down in Sioux City
U.S. District Court Judge Leonard Strand sentenced Coates to 420 months, or 35 years, in federal prison. He must serve five years of supervised release following his prison term.
Lawson received 120 months, or 10 years, in prison, followed by three years of supervised release. There is no parole in the federal system.
“The agents, officers, and deputies who investigated this case never stopped their efforts to find the truth. Their patience and dedication built a case that allowed us to call more than four dozen witnesses and introduce dozens and dozens of exhibits,” U.S. Attorney Leif Olson said.
FBI Special Agent in Charge Eugene Kowel said the sentences resulted from the persistence of investigators and prosecutors.
“The trafficking of drugs into our communities is not a victimless crime. It has a destructive effect on our neighborhoods and families,” Kowel said.
Coates and Lawson remain in U.S. Marshals Service custody while awaiting transportation to federal prisons.
Along with the O’Brien County Sheriff’s Office, the investigation involved the FBI, Bureau of Alcohol, Tobacco, Firearms and Explosives, Iowa Division of Criminal Investigation, Iowa Department of Natural Resources, Iowa State Medical Examiner’s Office, Nebraska State Patrol, Plymouth County Sheriff’s Office, Hitchcock County Sheriff’s Office, Goodland Police Department and the Sioux City-based Tri-State Drug Task Force.
