Police issued a murder warrant in one of eight Midwest killings that may be connected to the same person of interest who is the focus of a massive manhunt.

Authorities said Tuesday that an intense search is under way for 28-year-old Nicholas Troy Sheley.

They've obtained a warrant for his arrest on charges of first-degree murder, aggravated battery and vehicular hijacking in the death of Ronald Randall, who was beaten to death and left behind a Galesburg, Ill., grocery store Monday.

Authorities said Tuesday that there was "evidence at each of these scenes" linking Sheley to the crimes.

An autopsy shows the 65-year-old died from blunt force trauma to the head.

Police say Randall's 2007 pick-up truck was found in St. Louis, and evidence discovered inside points to Sheley's involvement.

Illinois State Police say Sheley has been named a person of interest in at least five other killings and may be connected to two in Missouri.

Sheley is considered "armed and dangerous."

Among the homicides believed to be linked to him is one in which an elderly man was beaten to death and left in the trunk of his car.

State police are offering a $25,000 reward for information leading to Sheley's arrest.

Authorities called him a person of interest in at least five homicides, including the deaths of four people whose bodies were found in an apartment in the western Illinois town of Rock Falls, about 116 miles west of Chicago.

State Police Sgt. Thomas Burek said Sheley is an acquaintance of one of those found inside the apartment.

Sheley also is believed to have connections to a recent homicide in Galesburg, a community about 60 miles southwest of Rock Falls, and two slayings about 250 miles further south in Festus, a Missouri suburb of St. Louis, Burek said.

On Monday, the bodies of two men, a woman and a child were discovered in the apartment after a well-being check in Rock Falls. Police wouldn't say who made the request for the check, but they believe one of the victims also is connected to 93-year-old Russell Reed, a Sterling man whose body was found stuffed in a trunk last week.

Authorities there say Reed died of blunt force trauma. Sterling is about 2 miles from Rock Falls.

The Whiteside County State's Attorney's office said the person of interest, who also is from Sterling, hasn't been charged in connection to any of the deaths, though there is a warrant for his arrest in a June 14 home invasion.

All eight victims appear to have been killed by blunt force trauma to the head.

Public records show he has a lengthy criminal record, including multiple convictions for robbery, drug and weapons charges.

Sheley is described as a white male, 28 years of age, 511, approximately 165 pounds, with green eyes and brown hair. He has tattoos on his arms, chest, and shoulders. He has a criminal history of armed violence and resisting arrest.

He had been seen Monday evening in Collinsville, an Illinois suburb of St. Louis.

On Tuesday morning, police in tactical gear searched a Collinsville apartment building for a person of interest in a double homicide in Festus, Mo., but "were unable to locate the guy," Collinsville police Sgt. Rich Wittenauer said.

Wittenauer said the search was at the behest of the St. Louis Area Major Case Squad investigating the slayings of a man and woman found dead Monday behind a Festus gas station. Investigators were looking for the couple's pickup truck.

Police are advising the public not to approach Sheley, but instead to call authorities immediately at the tip hotline, 866-219-8333.

The Associated Press contributed to this report.