Cheyenne man charged with murder in toddler’s death

Michael Cummo, Wyoming Tribune Eagle photo Stuffed animals and toys hang as part of a memorial for 2-year-old Athian Rivera Tuesday, Feb. 23, 2021, at the Lexington Hills apartment complex in south Cheyenne. Rivera’s body was found in the dumpster during a search for the then-missing toddler.

CHEYENNE – Wyatt Dean Lamb, a suspect in the death of 2-year-old Athian Rivera, has been charged with the toddler’s murder, the Laramie County District Attorney’s office announced late Monday afternoon. 

Lamb is charged with first-degree murder and 10 felony counts of child abuse with injury. His case is set for a preliminary hearing at 9 a.m. Aug. 6 in Laramie County Circuit Court. 

After an initial appearance Tuesday morning, his bond was set at $1 million.

Lamb was arrested in February for violating bond conditions in a separate case, and he has been held without bond in the Laramie County jail since March and is awaiting trial in that case. 

“I commend the Cheyenne Police Department, the Laramie County Coroner and the Wyoming State Crime Lab for their collective efforts in this case,” Laramie County District Attorney Leigh Anne Manlove said in her Monday email statement to the media. 

Athian was reported missing by his mother, Kassandra Orona, around 1 p.m. Feb. 19. 

His body was discovered around 3 that afternoon in a dumpster located just outside an entrance to Orona’s apartment, located in the 400 block of Desmet Drive. 

The toddler died from a cerebral edema with herniation caused potentially by blunt force trauma, restriction of oxygen, or both, according to a probable cause affidavit filed Monday in Laramie County Circuit Court. 

Laramie County Coroner Rebecca Reid determined Athian died between 11 a.m. and 1 p.m. Feb. 19. His body was wrapped in a fitted bed sheet and a blanket, which were inside five black plastic trash bags, according to the affidavit. 

Forensic pathologist Dr. James Wilkerson noted “scattered blunt force injuries over much of the body,” including multiple contusions and abrasions, as well as burn marks on the toddler’s genitals, upper legs and groin area consistent with a handheld torch found at Orona’s apartment, according to an autopsy conducted by Reid and Wilkerson.

Wilkerson issued the autopsy report, signed on May 6, which ruled Athian’s death a homicide. 

He advised Reid that the cause of death was cerebral edema with herniation, with three contributing factors: blunt force injuries, suffocation and thermal injuries. He said Athian was the victim of “non-accidental trauma,” according to the affidavit. 

Wilkerson also observed complete or partial collapse of a lung or lung area, which he said was caused by suffocation or manual strangulation. 

The autopsy, conducted Feb. 20, was observed by two Cheyenne police detectives.

Bond conditions set in March 2020 in a separate case by a Laramie County Circuit Court judge prohibited Lamb from having contact with Orona and from being within one block of her home, according to court documents. Lamb was charged with felony strangulation of a household member, misdemeanor property destruction and interference with a peace officer after an incident involving Orona. He is currently awaiting trial in that case. 

On March 4, 2021, Lamb entered a denial to two bond revocation accusations filed by the state, including that he violated his bond conditions in the strangulation case by living with Orona since August 2020.

Lamb was identified as a suspect in Athian’s death by the Cheyenne Police Department on Feb. 23, when the department announced it had recommended charges of murder and aggravated child abuse against Lamb to the Laramie County District Attorney’s office. 

According to court documents: Orona was interviewed by a Cheyenne police detective at 4 p.m. Feb. 19, and again on Feb. 20 and 22. 

She said she lived in the apartment with Athian and her two other young children, and that Lamb had moved into the apartment with them in August 2020. 

Orona told a detective she had to be at work at 5:30 p.m. Feb. 18 and left the three children in Lamb’s care, as she normally did while at work. 

She communicated with Lamb throughout her shift. At one point, Lamb told her Athian had vomited and was coughing. She told Lamb to keep an eye on the toddler and that she would take him to the doctor in the morning, she said. 

She returned home at 3:30 a.m. and went to check on the children, who were sleeping together in the same bed, as they often did. As she was putting a blanket on them, she said Lamb turned out the hall light, and she was unable to see. When she asked what he was doing, he turned the light back on and walked away. 

Orona then smoked marijuana with Lamb in their bedroom until about 4:30 a.m., when they both fell asleep. 

The next morning, Orona said, Lamb asked her if they had clean sheets. He said he wanted to change the children’s sheets because Athian had vomited earlier, that he would take care of it and not to worry about getting up. Orona told the detective Lamb was “being nicer than normal.” 

At around 8:30 a.m., Lamb asked Orona to drive her daughter to Goins Elementary School because he was worried she would be late. Orona said this was out of the ordinary, and that even if the girl was late to school, Lamb would walk with her because it was such a short distance. 

The three left the apartment, leaving behind Athian and his brother, who were still in bed. 

Orona said she and Lamb returned to the apartment at about 8:40 a.m. and smoked marijuana together. Athian’s brother was awake, but Orona said she did not see Athian and believed he was still asleep. 

Orona went back to bed at 9:30 a.m. While she was in bed, Orona said Lamb was going to do chores, and that she heard him opening trash bags at one point. 

At about 12:15 p.m., Orona said Lamb woke her up and told her Athian was missing, and that the apartment door was open. 

Orona said she panicked and searched the interior and exterior of the apartment, separating from Lamb while they were outside looking. Orona said the apartment complex’s maintenance man helped her search for Athian, and the property manager encouraged her to call the police, which she did around 1 p.m. 

Lamb then left the apartment because of an outstanding arrest warrant, but returned around 1:30 p.m., while Orona was being interviewed by detectives. 

Lamb told detectives he lived in the 2500 block of Deming Drive with a roommate. 

He said he was with the children on Feb. 18, beginning at around 3:30 p.m., and that Orona went to work at 5:30 p.m. He said he put Athian and his brother to bed around 8 p.m., and that Athian vomited once during the night. He said he put the older girl to bed between 10 p.m. and 10:30 p.m., and that he checked on the boys, who were sleeping. 

Lamb said he went back to his apartment at about 3:40 a.m., after Orona returned home from work. 

He said he was awoken by Orona around 11:20 or 11:40 a.m., when she called him to tell him Athian was missing and that she had called 911. He said he then took a taxi to Orona’s apartment. 

When a detective asked Lamb if he was willing to go to the police department for further questioning, the detective said Lamb looked toward the window that provided a view toward where Athian’s body had been found. Lamb then appeared to faint and was taken to Cheyenne Regional Medical Center. 

Officers discovered Lamb had previously lived at the Deming Drive apartment, but had moved out around August 2020. A detective also found the taxi service Lamb described did not exist in Cheyenne, and all of the city’s other taxi services did not transport anyone to Orona’s apartment. 

Orona’s manager at her workplace provided Orona’s timecard for Feb. 18 and Feb. 19, as well as a video of the business’s interior, which showed Orona working during the times she told detectives. 

After learning Athian had died, Orona told detectives she believed Lamb might have been trying to keep her away from Athian the morning of Feb. 19 to hide what he had done. 

During an interview with detectives, the apartment complex’s maintenance man said he was in front of the management building at about 12:50 p.m. Feb. 19 when he heard a “blood-curdling scream.” He ran toward the scream and found Orona, who said her 2-year-old had gotten out of their apartment and had been missing for about 45 minutes. The maintenance man began to help Orona look for Athian. 

He said he remembered a trash truck had emptied the apartment complex’s dumpsters between 12:30 p.m. and 12:45 p.m., and he said he told police they should stop the trash truck. 

He later told detectives that, after his initial interaction with Orona, he saw a man on a bicycle on the south side of the complex. He said he thought it was odd that the man simply stared at him and did not ask what was going on or offer to help. He later identified the man as Lamb after seeing a photo of him. 

The apartment complex manager told detectives she was contacted by Orona outside her apartment at about 1 p.m. Feb. 19. She said Orona was upset and crying and told her Athian was missing. The manager said she saw Lamb in the apartment, that his face was blank, and he did not seem upset, “worried or flustered.” 

A school resource officer interviewed Orona’s daughter at around 3 p.m. at her school. The girl said her mother and her mother’s friend, “Wyatt,” had brought her to school that morning and left her brothers at home because they were sleeping. She said Athian had vomited sometime during the night. 

A surveillance video from the elementary school obtained by police showed Lamb, Orona and the girl arriving in Orona’s vehicle at about 8:40 a.m. Feb. 19. 

A trash truck operator for the city of Cheyenne confirmed he emptied the dumpster close to Orona’s apartment at about 12:35 p.m. Police secured and sealed the dumpster Athian was found in, taking it to the police department. 

During a search of Orona’s apartment at 7:32 p.m. Feb. 19, detectives found a roll of black plastic trash bags consistent with the bags Athian was found in, along with other sheets that matched the one he was wrapped in. Upon searching the dumpster, detectives found another trash bag containing items similar to those found in Orona’s apartment. 

Lamb called Orona at 1:24 p.m. Feb. 21 from the Laramie County jail. Orona confronted Lamb about Athian being found in sheets and trash bags from the apartment, recounting the events of Feb. 18 and 19 to Lamb, saying she’d been thinking about Lamb’s actions during those days and accusing Lamb of lying. 

DNA tests and fingerprints seemed to show Lamb had tied the knots on the trash bags Athian was found in.

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