Boston prosecutors dismissed a case on Thursday against four undocumented immigrants accused of raping a woman and beating up her boyfriend at knifepoint earlier this month.

The Incident

The incident took place on March 13 when an unnamed couple was walking home from a store in Framingham, Boston. That's when they allegedly ran into four Guatemalan natives -- Elmer Diaz, 19, Ariel Diaz, 24, Adan Diaz, 32, and Marlon Josue Jarquin-Felipe, 27, -- who they said were "intoxicated and stumbling," according to court records.

One of the immigrants made a friendly gesture and offered the man a beer. However, another made a sexual advance towards the man's girlfriend. After she refused his proposition, the victims say some of the men dragged her inside a nearby Hollis Street apartment, while one big guy held the boyfriend back.

The woman told police that Ariel, Elmer and Jarquin-Felipe then proceed to sexually assault her inside the apartment.

"They began carrying her against her will," prosecutor Susan Harris said during the men's arraignment. "She said she tried to stop them and had her feet down, but one of them picked her legs up and they carried her into an apartment."

After her boyfriend managed to get inside the apartment, he was head-butted several times by Ariel. He also says Ariel pulled out a large chef's knife and tried to slash him, saying, "I am going to carve you up and rape your girl."

Eventually, the boyfriend smashed one of the men with a beer bottle and was able to escape the apartment with his girlfriend, officials said.

"After we got out, we got down to the street and she was screaming, 'Police! Police!' and I was like, 'Don't stop, just keep running,'" said the man.

The Hearing

During a hearing held in Framingham District Court on Thursday, prosecutors dropped charges against the immigrants after new video evidence and witness statements were presented, casting doubt on the allegations.

"The prosecution saw a problem with the witnesses' stories, and brought it to our attention, as is their duty," said John Daly, an attorney representing one of the suspects.

After the evidence emerged, the couple refused to testify against the suspects and invoked their Fifth Amendment right against self-incrimination. As a result, prosecutors were forced to dismiss the case. Without that testimony, "the commonwealth has insufficient evidence upon which to proceed," said Assistant District Attorney Joe Gentile.

The men were originally charged a host of crimes, including rape, indecent assault and battery, assault with a dangerous weapon, and kidnapping. However, after all of the charges were dropped, they were turned over to immigration officials.

"U.S. Immigration and Customs Enforcement intends to assume custody of all four individuals," confirmed ICE spokesman Daniel Modricker.

According to federal immigration officials, Ariel Diaz and Jarquin-Felipe were previously deported in 2014 before they illegally reentered the U.S. at some point.