BAGHDAD, Iraq (CNN) -- Two American contractors being held by Iraqi authorities were handed over to U.S. custody on Sunday, the U.S. Embassy said.
Jason Jones and Micah Milligan were the last of five U.S. contractors taken into custody June 3 in a pre-dawn Green Zone raid by Iraqi and U.S. personnel, a security source told CNN.
Three were previously released on bond.
The two transferred Sunday "remain in custody pursuant to Iraqi judicial orders," a U.S. Embassy spokesman said.
The five were initially told they were being held in connection with the death last month of another contractor, James Kitterman, according to a source close to the five.
Iraqi government spokesman Ali al-Dabbagh also said the men were detained based on information linking them to the Kitterman slaying.
Kitterman was found bound, blindfolded and fatally stabbed in a car in Baghdad's Green Zone -- the high-security area in central Baghdad that contains the U.S. Embassy and key Iraqi government buildings -- on May 22. The 60-year-old Houston, Texas, resident owned a construction company that operated in Iraq.
But on Monday, the men were told they were being held on suspicion of having unregistered weapons, according to a judicial source.
An Iraqi investigative judge ordered the release of three of the contractors -- Mark Bridges, Donald Feeney and his son, Don Feeney III -- on Wednesday, saying there was insufficient evidence linking them to the killing.
Jones and Milligan were also cleared of suspicion in Kitterman's killing by the judge. However, a spokesman for Iraq's Higher Judicial Council, said the two contractors were being held on charges involving "illegal substances" found on the men when they were taken into custody.
Those who have been released are not allowed to leave the country because the investigation is ongoing and the judge may want to question them again, al-Beeraqdar said.
Under Iraqi law, after a person is detained, an investigative judge questions the accused and assesses the evidence. The judge then decides whether there is sufficient evidence, and either refers the case to trial or dismisses it.
Except for Jones, the contractors work for the Fayetteville, North Carolina-based Corporate Training Unlimited, a security firm.
CNN's Jomana Karadsheh and Mohammed Tawfeeq contributed to this report.