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Denver man charged with murder after girlfriend found dead on train in 2016

The suspect has a lengthy history of domestic violence, according to an arrest affidavit
Posted at 5:07 PM, Oct 31, 2023
and last updated 2023-10-31 19:07:40-04

DENVER — A Denver man has been charged with allegedly suffocating his girlfriend on a train ride from Wisconsin to Denver in 2016 — a final act after a lengthy history of domestic violence, according to an arrest affidavit.

Angelo Valentino Mantych, 41, has been charged with first-degree murder after his girlfriend, 28-year-old Marina Placensia was found deceased, according to the Denver District Attorney's Office.

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The charges stem from Aug. 30, 2016, when Placensia and her four young children boarded an Amtrak train in Racine, Wisconsin, where she lived, to go to Denver. She had three of the children with Mantych.

When the train arrived at Union Station in Denver on the morning of Sept. 1, Placensia was deceased. Resuscitation efforts began, but she was pronounced deceased at 7:54 a.m. Mantych was on the platform area of the station and according to an affidavit, "appeared to be upset, crying and vomited several times."

During a conversation with police, Mantych said they had left Wisconsin to move to Denver. He said about 20 minutes before the train was due to arrive in Denver, he tried to shake Placensia awake, but she did not respond, according to the affidavit.

Police at the scene noted several bruises on her body that "appeared to be consistent with an assault or struggle," the affidavit reads. However, an investigator said he believed none of them were an "obvious case of death." When police asked Mantych about the bruising, he said his girlfriend had been "banged up from moving." An autopsy later found blunt impacts to her head, trunk and extremities.

Placensia's brother reached out to police that same day to say they should look into Mantych, and called him abusive.

The following day, Sept. 2, 2016, Mantych spoke with police again, this time over the phone. He said they had lived in Wisconsin for three years and his girlfriend had never been hospitalized there for anything. He told police the family was excited to move to Denver and were planning their future.

About a week after Placensia's death, police spoke with the family's acquaintances in Wisconsin, who said Mantych beat Placensia the day before the move and that the couple fought often. Several other people told police Mantych was abusive, both physically and mentally. One person said he beat Placensia daily, according to the affidavit, and another said she had to go to a hospital multiple times for her injuries from the assaults. Some witnesses also said they believed Mantych was abusing the children based on what they heard through open windows.

A friend of Placensia told police that Placensia had talked with her family over the phone about moving back to Colorado to escape Mantych, but he had overheard the call and told Placensia "he would kill her if she left with the children," according to the affidavit. Others told police that she would wear sweaters and sunglasses all summer to cover bruises, according to the affidavit.

Family planned to have Placensia live with them in Denver once she had arrived.

Placensia's autopsy showed 35 internal and external injuries. However, the autopsy report noted that they did not explain her death. The cause and manner of death was listed as undetermined, according to the affidavit.

As part of the investigation, police spoke with the Racine Police Department in Wisconsin. According to one of their reports from March 13, 2015, Mantych had punched Placensia's ear several times and she lost hearing in that ear. He was arrested and charged with assault after that incident.

The investigation continued for several years. Other witnesses spoke with police in 2023 and said they had seen abusive behavior regularly from Mantych.

On May 18, 2023, a doctor confirmed he believed Placensia's cause of death was the first result of asphyxia from suffocation and said her injuries are consistent with suffocation cases in both living and deceased patients, according to the affidavit. He said he believed her injuries were the result of an assault, including blunt force trauma and suffocation.

That report reads: "Suffocation was the cause of Ms. Placensia's homicidal death and occurred from the application of pressure to her face, obstruction of the nose and mouth, and created a hypoxic condition which led to her death... The manner of death is homicide."

An at-large warrant was signed for Mantych's arrest on Oct. 30.

He is due in court on Nov. 1 at 8 a.m.

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