The standoff ended late Friday night.
One-thousand and ten miles from a murder scene in Colorado, the suspected killer took his own life in Chicago.
Tyler James Martin has been on the run since Tuesday. That's when he's suspected of running his ex-girlfriend off the road and then killing her.
"I watched this other vehicle pull up beside her, a male get out of his car and shoot her several times," a witness said.
Police in the Denver suburb of Wheat Ridge found evidence that Tyler Martin was stalking his ex-girlfriend Amber Cremeens. The two carried on a relationship for nearly eight years. But it ended last year.
Inside Mr. Martin's Colorado home, investigators say they found evidence Martin has been studying up on his ex's daily routine and following her.
The woman's new boyfriend reported the alleged stalking in this 911 call to police.
Tyler Martin is originally from northwest suburban Wonder Lake. Colorado police alerted law enforcement in Illinois that he may be heading home and to consider him armed and dangerous.
Two alert Chicago police officers did just that, spotting the suspect's dark green Mercury Mystique in Logan Square. Martin was inside but quickly fled into a nearby apartment building. The officers say he had three semiautomatic weapons with him and after a three-hour standoff used one to take his life.
"When they confronted him in the vestibule he did display that other weapon and that's when the standoff ensued," said Deputy Chief Juan Rivera, Chicago Police Department.
It is believed the standoff actually took place in the apartment building of one of the murder suspect's relatives. Police said throughout the entire standoff the suspect refused to have any talks with the police negotiator.