A Utah mother and her young son went missing in 2015. Authorities now believe her boyfriend killed them.

Two years ago, 23-year-old Emily Almiron and her 3-year-old son, Gabriel, disappeared.

No one has seen the Utah County woman or her child since Sept. 8, 2015 — the day her boyfriend, Christopher Richard Poulson, told police that he broke up with the woman, and she left their Orem apartment with her young son.

She never used her cellphone again, according to prosecutors, and her bank account was never accessed.

She never went back to her job at an Italian restaurant in Orem, and never went to another class at the massage therapy school she was attending.

Almiron’s ex-husband reported her missing to police days later, after she did not show up for a child custody exchange.

Now, authorities believe the woman’s boyfriend killed her and her child that September night — and, after a two-year investigation, Poulson was arrested over the weekend in Hawaii.

The 28-year-old man was charged last week in 4th District Court with two counts of first-degree felony aggravated murder and one count of second-degree felony obstruction of justice, according to charges unsealed Monday.

Poulson told investigators multiple times over the past two years that he hasn’t seen Almiron since he broke up with her in September after he found drug paraphernalia in their apartment.

Prosecutors allege that Poulson murdered the woman and her son, wrapped them in sheets and then “buried or otherwise disposed of and concealed their bodies.”

Their bodies have never been found, but authorities say numerous pieces of evidence add up to murder.

The day after the mother and son disappeared, Poulson bought a shovel and work gloves and then turned off his cellphone, according to a probable cause statement filed in court. The phone was turned back on three hours later and police traced it to a rural area of Payson.

Prosecutors allege that geolocation data from Poulson’s phone show he took a trip Sept. 11, 2015, to St. George, where he abandoned Almiron’s red Toyota Prius with the keys and some of her belongings inside.

The car was found in April 2016 and was searched by police. But authorities say the only fingerprints that were found on the bags of Almiron’s belongings were Poulson’s. He returned to Utah County via a shuttle service, charges state.

Though Poulson had originally told investigators that Almiron usually drove him around in her car, police discovered that the man owned a Ford Mustang, which he sold below value days after the disappearances. Police tracked down and searched the vehicle, and a cadaver dog “indicated” on the trunk area three times, according to charging documents.

Poulson also told other lies to police as they investigated the disappearances, prosecutors allege, including omissions about being a drug user himself — though he had blamed the break-up on Almiron using drugs.

Though authorities have not said how they believe the mother and son were killed, prosecutors noted in court papers that a friend who moved into the Orem apartment shortly after Almiron’s disappearance noticed a hammer was missing. Another friend reported to police that weeks after the disappearances, Poulson had showed him a gun during a party at the Orem apartment and asked about scratching off the serial number and whether it could be traced by police.

“Soon after being confronted with all of this evidence, defendant offered no explanations for his clear involvement and almost immediately moved to Hawaii,” Deputy Utah County Attorney Sam Pead wrote in charging documents.

Poulson had been living in Smithfield as recently as May, according to court documents filed in connection to a DUI case in Cache County. In July, he pleaded guilty to charges there, but an arrest warrant was issued a month later when he didn’t show up for his sentencing.

Court records show that Poulson pleaded guilty to another Cache County DUI case in 2007.

No court dates have been set in the murder case, pending Poulson’s extradition back to Utah. Officials said they would release more details about the case at a Tuesday news conference.