Two pressure cookers were used in last month's Boston Marathon bombings.
Hussain Al Khawahir was being held in Detroit on allegations of lying to Customs and Border Protection agents and of using a passport with a missing page. He was arrested Saturday.
His nephew, Nasser Almarzooq, told The Associated Press that he had asked his uncle to bring him the pressure cooker so he could make lamb. The college student said two pressure cookers he bought in the U.S. were "not good at all," and said the ones available in Saudi Arabia are higher quality.
"I'm Arabic," said Almarzooq, who is studying mechanical engineering at the University of Toledo in Ohio, about 55 miles south of Detroit. "I always use pressure cookers to cook."
Almarzooq said his uncle was coming to visit him for a couple weeks.
A criminal complaint alleges that Al Khawahir arrived at the airport Saturday on a flight from Saudi Arabia via Amsterdam, and that he told agents he was visiting his nephew.
He originally said he brought the pressure cooker with him because pressure cookers aren't sold in America, then later said his nephew had bought one but it "was cheap" and broke after one use, according to the complaint.
Agents said they also noticed a page was missing from Al Khawahir's passport from Saudi Arabia. He told them he didn't how it had been removed, and said the document had been locked in a box that only he, his wife and three children have access to in his home, according to the complaint.
Al Khawahir was read his Miranda rights, which he said he understood, and he invoked his right to remain silent, according to the complaint.
Gina Balaya, spokeswoman for the U.S. attorney's office in Detroit, said Al Khawahir made his initial court appearance Sunday, but his Monday detention hearing was delayed until Tuesday afternoon. A message seeking comment was left with his defense attorney.
Authorities have said that in the Boston Marathon bombing, brothers Tamerlan and Dzhokhar Tsarnaev set off two shrapnel-packed pressure-cooker bombs April 15 near the race finish line. The attack killed three people and injured more than 260 others.
On Monday, Almarzooq said he was concerned about his uncle and hadn't been told anything since his uncle was arrested Saturday. He also vehemently denied any wrongdoing.
"If I wanted to do something stupid like this, should I just take my uncle from Saudi Arabia to buy me a pressure cooker?" he said. "It's legal here."