A Westmont man who police say stabbed his father to death, led police on a high-speed chase and injured four people in a chain-reaction car crash before finally ramming into a tree last week remains in the hospital, but has been upgraded from critical to serious condition.

Rostyslav Demtyso is in serious condition at Advocate Good Samaritan Hospital in Downers Grove, according to a hospital spokeswoman.

Four others were involved in the crash: a driver and two occupants of a sport utility vehicle, and a driver of a third vehicle. All except one of the passengers in the SUV were taken to local hospitals. They sustained serious but not life-threatening injuries, Westmont Police Chief James Ramey said.

The Westmont Police Department is working with the DuPage County State’s Attorney’s office in determining what charges will be filed against Demtyso. Ramey said he will be charged as soon as his medical condition improves.

At about 9:15 p.m. Nov. 19, Westmont police responded to a report of a fight on the 200 block of North Wilmette Street. Police said Demtyso, 28, 233 N. Wilmette St., stabbed his father, Oleg A. Demtyso, 53, of the same address.

When the first officer arrived on the scene less than two minutes after the original call, police said the suspect already had left in a silver Dodge Stratus and was seen by another officer driving south on Cass Avenue near 55th Street.

The officer attempted to stop the car, but the suspect drove away at a high speed, according to police. Police pursued the driver until his vehicle hit a silver sport utility vehicle that also was driving south on Cass Avenue at the intersection of 73rd Street in Darien. The SUV then hit another vehicle that was going north on Cass Avenue. The suspect’s vehicle then hit a tree on the west side of Cass Avenue.

Police and fire department personnel administered emergency aid to the stabbing victim and took him to Good Samaritan Hospital, where he was pronounced dead a short time later, according to police.

Though detailed statements on evidence are premature, Ramey said, the police investigation has established that the stabbing incident occurred during an argument between the father and son.

“Unfortunately, this type of violence is the most common type of homicide in the country, particularly in a community like Westmont,” Ramey said in a statement. “Despite this horrible incident, Westmont is still a very safe community. We should not allow this isolated incident to cause us to lose sight in that fact.”

The crash was investigated by the Darien Police Department with assistance from accident reconstruction investigators from the Felony Investigative Assistance Team, a DuPage County joint investigative task force.

Police Chief Ramey said this is the first homicide in Westmont since 2005, when Lewis Watson stabbed his neighbor after an argument in the parking lot of their apartment complex. He was sentenced to 14 years in prison in May.

Ramey said because the most recent incident involved family members and the suspect is not at large, there is no reason for members of the community to be alarmed.

“The Westmont Police Department extends our sympathies to the victim’s family and our concern to those injured in the traffic accident,” Ramey said in a statement.

Gilbert Flores, the next-door neighbor of the Demtysos, said his son, who was home the night of the stabbing, said he heard arguing outside. Flores said when his son looked outside, he saw a body lying in the driveway and police were on the scene.

Nowena Lalonde also lives on the 200 block of Wilmette Street. She was not at home at the time of the incident but said she heard about it later. She said she did not know the family well, but met the victim’s wife once.

“I’m very surprised that this happened,” Lalonde said.

No one answered the door Thursday or Monday morning at the Demtyso residence, a two-story brick house set in the middle of the block. Two cars, a Volvo and a Jeep, were parked in the driveway.

The Demtysos have an unlisted phone number.