BOSTON (AP) -- Federal investigators and a defense lawyer gave contrasting accounts Wednesday of the circumstances surrounding the confessions by two friends of the Boston Marathon bombing suspect, who are accused of tampering with evidence in the days after the bombing as authorities conducted a massive manhunt for their friend.During a federal hearing, FBI agents painted a picture of a pair of college friends of the bombing suspect, Dzhokhar Tsarnaev, as willing participants in the investigation who agreed to talk and allowed authorities to search their apartment days after the April 15, 2013, attack. They were read their rights and told that they were not under arrest, Special Agent Farbod Azad testified. Documents showing that one of the friends, Dias Kadyrbayev, signed a consent form to have his apartment, car and laptop searched were shown in court, as well as a form listing his rights that he signed as well.The defendants did not seem tense during the April 19 interviews and even cracked jokes, Azad said. When he asked if he could speak with the two the next day, they replied that they had "plans on 4/20," a reference to smoking marijuana, Azad added.But Kadyrbayev's lawyer, Robert Stahl, said that investigators obtained confessions from them without a lawyer present, under strenuous and lengthy circumstances and without a search or arrest warrant. They were also held shirtless for several hours, despite asking repeatedly for a shirt, Stahl said. He added that several armed officers swarmed the apartment before the two men were brought to the station, where they admitted to taking Tsarnaev's laptop and a backpack containing fireworks from his dorm room at the University of Massachusetts Dartmouth, about 60 miles from Boston.After speaking with investigators, Kadyrbayev and the other friend, Azamat Tazhayakov, both Kazakhstan nationals, were allowed to leave but were arrested the next day on immigration charges.Kadyrbayev is charged with tampering with evidence. His lawyer was in court in an effort to have his client's confession kept out of his trial.Kadyrbayev will likely take the stand Thursday or Friday, depending on the length of testimony by other prosecution witnesses. A judge ruled this week that the motion to suppress his confession will not be considered without him being questioned. Tazhayakov and a third friend of Tsarnaev's who was charged, Robel Phillipos, declined to testify. Their attorneys said they will likely revisit their own attempts to have their clients' confessions suppressed during their trials.The three men will be tried separately in Massachusetts this year. Tazhayakov and Kadyrbayev have been held without bail for more than a year. Phillipos, of Cambridge, is charged with lying to investigators. He has been held under house arrest.All have pleaded not guilty.Tsarnaev, 20, has pleaded not guilty to 30 federal charges related to last year's deadly bombing. His trial is set to begin in November.