Three Somali-American men accused of trying to assist Islamic State put a lot of effort and planning into their attempts to travel overseas to fight with the militant group in Syria, and they also talked openly of killing people, prosecutors said on Wednesday.

Minnesota residents Mohamed Farah, Abdirahman Daud and Guled Omar are charged with conspiring to provide material support to Islamic State and commit murder outside the United States, according to a brief filed by prosecutors. 

The men are part of a group of 10 people that faced similar federal charges. Six have already pleaded guilty to providing material support to Islamic State, and another is believed to be in Syria, said Ben Petok, a spokesman for the U.S. Attorney’s Office for the District of Minnesota. 

In an opening statement, Assistant U.S. Attorney Andrew Winter told the jury in U.S. District Court in Minneapolis that the three defendants worked “tirelessly” to travel to Syria to join Islamic State.

Winter showed slides and read quotes by the three defendants from conversations tape recorded by the government, in which the men discuss their criminal plans.

Winter quoted Omar discussing how he would help Islamic State return to the United States: “They’ll do crazy damage. I swear to God, we have a big opportunity.”

Winter also quoted Omar talking about killing the “kuffar,” an Arabic term for disbeliever.

Defense attorneys were scheduled to make their opening statements later.

The government’s evidence will also include murders committed by the Islamic State group and videos watched by the defendants depicting the use of explosives and firearms. 

Along with the conspiracy counts, Farah and Daud are charged with perjury, and Farah with making a false statement to Federal Bureau of Investigation agents. 

Omar is also facing a charge of attempted financial aid fraud for trying to use $5,000 in federal student aid to fund travel to Syria, prosecutors said.

Each defendant faces up to life in prison. They are in federal custody. 

From March 2014 to April 2015, a group of individuals, including the defendants, met multiple times at various locations and agreed to travel to Syria to fight for Islamic State, prosecutors said. 

Prosecutors say the three defendants helped each other with plans to travel to Syria, such as getting passports and money, advising each other on how to contact the Islamic State and agreeing on ways to keep plans secret from law enforcement.