Wilbur Martinez-Guzman, 19, was arrested on Saturday in Carson City, Nevada

U.S. immigration authorities say a man suspected of killing four people in Nevada over the last few weeks is from El Salvador and entered the United States illegally.

Murder suspect Wilbur Martinez-Guzman, 19, had no criminal record or history of previous immigration violations, Immigration and Customs Enforcement said on Tuesday.

The agency did not have additional details on his alleged illegal entry to the U.S., including when and where it occurred. The agency's public affairs staff is furloughed because of the government shutdown.

The case shot to national prominence on Monday after President Donald Trump tweeted about the killings to support his case for the proposed border wall with Mexico.

Martinez-Guzman has been linked to the murders of four people in the Carson City area.

Investigators have not revealed a motive in the case.

On January 10, Connie Koontz, 56, (left) was murdered in her home in Gardnerville Ranchos. Three days later, Sophia Renken, 74, (right) was found dead in her home a mile away

On the night of January 10, Connie Koontz, 56, was murdered in her home in Gardnerville Ranchos, about 15 miles south of Carson City. Her aging mother, who lived in the home, found her body the next morning.

Three days later, 74-year-old Sophia Renken was found dead in her home about a mile from where Koontz lived.

Police immediately suspected the two murders were committed by the same suspect due to similarities in the cases.

Douglas County Sheriff Dan Coverley said that it was possible that the suspect targeted the women because of their age, gender and the fact that they appeared to live alone.

Then on January 16, the bodies of 81-year-old Gerald David, and his 80-year-old wife, Sharon, were found in their home on the southern edge of Reno, about 20 miles north of Carson City.

On January 16, the bodies of 81-year-old Gerald David, and his 80-year-old wife, Sharon (together above in a family photo), were found in their home on the southern edge of Reno

The couple were remembered as longstanding members of Reno's equestrian and rodeo scene.

Former Reno Rodeo Association president Tom Cates says he met Gerald and Sharon three decades ago and spent 'many miles and many hours together' on horseback with them.

Cates says Gerald David was previously the association's president and promoted a breast cancer awareness campaign by getting cowboys to show they were 'tough enough to wear pink shirts.'

Cates also was a member of the local Elks Lodge when David was the group's leader.

He says Sharon David was 'exuberant, bubbly, loved animals to the hills.'

Cates says the two were also members of a horseback social organization called the Nevada White Hats.

Martinez-Guzman has been jailed in Carson City since Saturday on possession of stolen property, burglary and immigration charges.

News reports listed his age as both 19 and 20, but court records show that he will turn 20 on February 2.

Authorities have said they expect to file murder charges against him shortly.

Carson City Sheriff Ken Furlong said at a Sunday news conference that federal immigration authorities told his office Martinez-Guzman had lived in Carson City for about a year and was in the country illegally.

Trump mentioned the killings on Monday in a tweet calling for his long-promised border wall.

‘Four people in Nevada viciously robbed and killed by an illegal immigrant who should not have been in our Country. 26 people killed on the Border in a drug and gang related fight,' Trump wrote.

He continued: ‘Two large Caravans from Honduras broke into Mexico and are headed our way. We need a powerful Wall!’