Sioux City, Iowa — The O’Brien County Sheriff’s Office is listed as one of the agencies that helped investigate a case for which two men have now been sentenced in the death of an 18-year-old from Nebraska.
The men were sentenced to a combined 45 years in federal prison.
The US Attorney’s Office says 48-year-old Floyd Clifford Coates, Jr., and 60-year-old Dennis Lawson, former brothers-in-law, were convicted by a jury of drug and obstruction-of-justice charges on November 25, 2025, after an eleven-day trial.
Coates, a.k.a. Cliff Coates, from St. Francis, Kansas, and Strubel, Iowa, was convicted of six counts, including drug trafficking, unlawful possession of firearms, and obstruction of justice. He was acquitted of two obstruction-of-justice charges related to allegations involving threatening witnesses.
Lawson, who is from Whiting, Iowa, was convicted of one obstruction-of-justice charge for threatening a witness. He was acquitted of drug-trafficking and other obstruction-of-justice charges.
Evidence at trial showed that in the spring of 2019, Coates was a member of a drug-trafficking organization that funneled pounds of methamphetamine from Colorado to multiple locations, including Iowa. Coates possessed firearms to protect his illegal drug operation.
On Easter weekend 2019, Coates arranged to make a drug resupply run to Kansas City, Missouri. He convinced an Iowa woman to drive from Sioux City, Iowa, and meet him in Blair, Nebraska, to help him with the drug run. She was then supposed to drive him to Kansas City and back. Coates traveled to Blair from Trenton, Nebraska, with another woman, 18-year-old Sunny Sramek. Coates and Sramek left Trenton in his wife’s white Ford Explorer. Sramek told friends and family that she was going to be on a day trip to Omaha with Coates and made no mention of going to Kansas City.
Coates and Sramek arrived in Blair. Coates left the Explorer and went into a home, but Sramek did not. Coates’ driver arrived at the home from Sioux City. Coates said nothing to her about Sramek. As the driver and Coates left the home, the driver saw Sramek’s motionless body in the Explorer. Sramek looked to the driver as if she had overdosed: fluids were coming out of her mouth and running down the center console, her bare foot was on the dashboard, and the front window was broken as if Sramek had kicked it violently as she died. Coates told the driver that he had given Sramek methamphetamine and that Sramek must have overdosed.
Coates abandoned his plan to make a drug run to Kansas City. He told the Sioux City driver to go to the home of his brother-in-law Dennis Lawson near Whiting, Iowa, on the banks of the Missouri River. The pair drove the apparently dead Sramek to Lawson’s home. The driver testified that after they arrived at Lawson’s residence, Lawson and Coates disappeared for a time. When they returned, Sramek’s body was gone. The driver testified that she and Coates then cleaned out the car, and that Lawson threatened her, saying that if she told anyone, “it would be her funeral.”
Coates later told other individuals that Sramek had overdosed. While detained awaiting trial, he told cellmates that he had killed Sramek after raping her. In both versions, however, he told people he had thrown Sramek’s body into the Missouri River to conceal evidence of his crimes. Coates told one person “no body, no case” and asked another “you can’t get charged with murder if there is no body, can you?”
Law-enforcement officers immediately gathered evidence tying Coates to Sramek’s disappearance. He had been the last to see her alive. Forensic analysis of the Ford Explorer revealed that it contained Sramek’s DNA. The analysis also suggested that she had struggled in that car. An FBI geologist testified that the window had been broken from the inside by three blunt-force impacts, consistent with a foot kicking it. A medical examiner testified that such convulsions were consistent with a person dying from a methamphetamine overdose. There was also evidence that someone, possibly Sramek, had bled in the Explorer. Further, the story Coates told to law enforcement about his movement that day was contradicted by other evidence. For example, he said that Sramek abandoned him while they were at the casino in Carter Lake, Iowa, but cell-phone location information showed he hadn’t been there.
Coates had previously been convicted of multiple crimes including burglary, false imprisonment, assault by a confined person, distribution of a controlled substance, possession of a deadly weapon by a felon, and witness intimidation. Lawson had previously been convicted of multiple crimes including domestic abuse assault, aggravated domestic abuse assault, and robbing the Onawa, Iowa, Pizza Hut.
Coates and Lawson were sentenced in Sioux City by United States District Court Judge Leonard T. Strand. Coates was sentenced to 420 months’ imprisonment. He must also serve a 5-year term of supervised release after the prison term.
Lawson was sentenced to 120 months’ imprisonment. He must also serve a 3-year term of supervised release after the prison term. There is no parole in the federal system.
“Seven years and three months ago, after Sunny Sramek left home, a thuggish coward and a cowardly thug are going to prison for their roles in her death,” said United States Attorney Leif Olson. “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. Thanks to their work, Sunny’s family and the communities that these criminals abused have finally received a measure of justice.”
“The sentences imposed on Coates and Lawson today are a direct result of the tenacity and relentlessness of the FBI agents, law enforcement officers, and prosecutors who led the search for Sunny and the effort to apprehend those responsible for her death,” said FBI Special Agent in Charge Eugene Kowel. “The trafficking of drugs into our communities is not a victimless crime. It has a destructive effect on our neighborhoods and families. The efforts by Coates and Lawson to conceal their actions never broke our resolve to investigate this horrific crime. Although today’s sentencings will not bring Sunny back, we hope they will bring some measure of comfort and closure to everyone who knew and loved Sunny.”
Coates and Lawson remain in the United States Marshal’s custody until they can be transported to a federal prison.
The case was investigated by a number of federal, state, and local law-enforcement agencies:
- Department of Justice (DOJ) Bureau of Alcohol, Tobacco, Firearms, and Explosives;
- DOJ Federal Bureau of Investigation;
- Goodland, Kansas, Police Department;
- Hitchcock County, Nebraska, Sheriff’s Office;
- Iowa Department of Natural Resources;
- Iowa Department of Public Safety (DPS) Division of Criminal Investigation;
- Iowa Office of the State Medical Examiner;
- Nebraska State Patrol;
- O’Brien County, Iowa, Sheriff’s Office;
- Plymouth County, Iowa, Sheriff’s Office; and
- Tri-State Drug Task Force based in Sioux City, which consists of personnel from the Drug Enforcement Administration (DOJ); Iowa Division of Narcotics Enforcement (DPS); Iowa National Guard; Nebraska State Patrol; Sioux City Police Department; South Sioux City, Nebraska, Police Department; South Dakota Division of Criminal Investigation; United States Marshals Service; United States Homeland Security Investigations; Woodbury County, Iowa, Attorney’s Office; and Woodbury County Sheriff’s Office.
