A Washington state man is behind bars for killing two women with a fillet knife after one of them dumped him, prosecutors say.

Marvin Ortiz-Montecinos, 29, faces charges for two counts of first-degree premeditated murder, according to the King County Prosecuting Attorney’s Office. Each charge includes a deadly weapons enhancement, which aims to increase the potential sentence.

The suspect was arrested over the weekend in connection to the early September murders of Victoria Aparicio Cruz, 26, and her roommate, Yaneth Gómez Hernández, 32, as stated by the King County Sheriff’s Office.

Cruz was stabbed over 20 times; Gómez-Hernández was stabbed at least 43 times and suffered other defensive injuries, authorities say.

Details of the gruesome incident are contained in charging documents obtained by Law&Crime.

“Both women’s hands sustained severe lacerations as they attempted to defend themselves from the defendant’s filet knife,” reads the criminal information. “In simple terms, this crime was horrific.”

Due to privacy concerns, prosecutors chose not to include images of the victims, according to one of the documents – while detailing the trauma inflicted on the women in particularly graphic terms.

“[B]oth women received neck wounds so large and deep it appears clear that the defendant was attempting to slice and saw at his victims, and not simply stab them,” the document continues.

Prosecutors claim the defendant “partially severed” the roommate’s spinal cord and fully severed the jugular vein and carotid artery of his ex – continuing to stab her in the back even after her death.

Investigators described the believed murder weapon as a “curved 7-inch, single-sided filet knife,” according to the charging documents.

On Sept. 8, a 911 call was made by another resident at the Montrose Apartments on 152nd Street in Burien – a medium-sized suburb located along the southern border of Seattle.

The calling witness actually happened upon the defendant – laying in the grass with an apparent injury to his neck and covered in blood, according to an affidavit of probable cause.

Authorities say that was all part of the plan.

Responding deputies noted that Ortiz-Montecinos said “my fiance” in Spanish – but nothing else that was intelligible.

“The male subject was covered in blood and as deputies began to check him for injuries they located multiple injuries that appeared to be consistent with penetrating stab wounds on the back of his head, his chest, and on his back,” the affidavit reads.

As the bleeding man was taken away in an ambulance, emergency medical services left his bloody clothes and a lone black sandal.

Meanwhile, a “visible trail of what appeared to be blood drops” led back to a third-floor apartment unit and the carnage inside where the victims were “completely soaked in blood,” according to the affidavit.

“One of the female subjects was completely nude, with a towel partially wrapped around her legs,” the affidavit goes on. “The second female was fully clothed. No one else was found inside.”

A slight amount of ransacking was also visible, deputies allege. The drawers and cabinets in the kitchen were open – but such evidence was not repeated in any other room in the unit.

During a hospital interview, the defendant allegedly pinned the violence on an “unknown black male,” the narrative reads. Ortiz-Montecinos allegedly said he fell asleep on the couch that night and woke to hear Cruz’s screams. By the time he went to check on her, however, “it was too late” and both women were already dead, according to the affidavit.

Then, the would-be assailant stabbed him repeatedly, Ortiz-Montecinos said, and “left him for dead,” investigators wrote in the affidavit.

“Marvin claimed he did not see the weapon used to stab him, nor did he have any further details about the black male who stabbed him,” the document goes on. “He then claimed the black male then fled the apartment through the front door, leaving the front door open. Marvin then left the apartment, through the open door, to find help.”

As the investigation went on, authorities came to believe Ortiz-Montecinos was the killer and that the purported “black male” was subterfuge.

Authorities say numerous inconsistencies supported the determination the defendant was the only attacker in the apartment that night.

State crime scene investigators used a chemical agent to track the presence of blood inside the unit, according to the affidavit.

“The chemical agent revealed only one set of footprints that included one bare footprint and one soled footprint with sole markings that visually match the sole of the sandal recovered from Marvin at the scene,” the document reads. “Lab technicians also located blood on the inside of the deadbolt of the front door of the apartment. The single set of footprints and the blood on the deadbolt together indicate that the door was manually locked from the inside at the time Marvin – and only Marvin – left the apartment during the incident.”

The defendant’s own timeline also did not add up, law enforcement allege.

To hear Ortiz-Montecinos tell it, he fell asleep on the couch sometime soon after 7 p.m. But, authorities say, his cellphone showed him texting Cruz at around 10:23 p.m. And those texts, investigators say, provide the motive the grim crimes that came soon thereafter.

Translated from Spanish, the first message from the defendant reads: “Tell me, you broke up with me, I want to tell you something,” according to the affidavit. Then, Cruz writes back to confirm the breakup and later to say she doesn’t want to hear “anything anymore” from her former boyfriend. Finally, at 10:25 p.m., after saying he would come over, Ortiz-Montecinos allegedly sent a final message: “I tell you.”

Some 61 minutes later, Cruz’s neighbor called 911.

The defendant is being detained in the King County Jail on $10 million bail. Ortiz-Montecinos is a Guatemalan immigrant and is now subject to a detainer issued by Immigration and Customs Enforcement.

A GoFundMe seeks to raise funds for Gómez Hernández’s 10-year-old son.