Crew members on a U.S.-flagged ship learned Friday that their questioning by Venezuelan investigators in an arms trafficking probe has been delayed until Monday.

Venezuelan authorities have held the ship in Maracaibo since August 29, and took its captain into custody on Wednesday.

The shipping vessel's crew had expected to give depositions on Friday, according to a crew member who asked to remain anonymous because of security concerns.

As of Friday night, prosecutors had yet to make a decision on the case, according to a manager of the ship's customs brokers. The manager asked not to be named because of the sensitivity of the situation.

The captain and crew members were all expected to give statements to investigators, the manager said. The crew member who asked to remain anonymous said there were 14 crew members on board, plus the captain.

Divers and drug investigators were inspecting the ship, and the captain was expected to be returned to move the ship from the docks to an anchorage in Maracaibo Bay on Saturday morning, the manager said Friday night.

The manager identified the captain as Jeffrey Michael Raider, 45, of Texas.

The crew member who asked to remain anonymous said via e-mail Saturday night that the captain in fact had been returned to the ship to command it during its move to anchorage in the bay.

The captain " is going back tonight. Every bit of news is speculative at this point," The crew member said in the Saturday night e-mail.

U.S. State Department spokesman Patrick Ventrell on Friday confirmed the ship and crew's detention.

"We understand this has to do with questions about customs paperwork for some rifles they had on board for self-protection," Ventrell told reporters. "We, of course, know that the high seas and that piracy have been a major topic in recent months and years, and so that's something we've been combating. And indeed, it's normal for many ships to have some type of self-defense on board."

U.S. officials are seeking more information on the case, and Ventrell said that the absence of a U.S. ambassador in Venezuela isn't hampering the American response. U.S. President Barack Obama nominated an ambassador for Venezuela in 2010, but the Caracas government wouldn't allow him to assume the post.

There is an active U.S. embassy in the country, however, and U.S. consular officials did visit the ship's crew members on Thursday night, according to the crew member.

"We still have a large mission in Venezuela with appropriate consular personnel," Ventrell said. "I don't want to get into hypotheticals about what our relationship could be with Venezuela. We are where we are, and we'll continue to raise it as appropriate through diplomatic channels."

The Venezuelan Embassy in Washington said that "this issue is being handled by our officials in Venezuela" and didn't have additional immediate comments Friday, spokeswoman Marielba Alvarez told CNN on Friday.

Officials in Venezuela, meanwhile, did not respond Friday to requests for comment.

Soldiers boarded the ship Wednesday, herded the crew into the mess and met with Raider before taking him away, the crew member who asked to remain anonymous said by e-mail Thursday evening. Arrest warrants have been issued for the entire crew, according to this crew member, who added that he believes that authorities mostly want to talk to the crew for depositions.

The situation appeared tense, but the manager of the ship's customs brokers said the government's actions have not been aggressive and that both sides are cooperating and being respectful.

"It's a legal process, but no one's rights have been violated," the manager said.

The crew member, in another e-mail to CNN on Friday, said that though his colleagues were upset, no one had been mistreated.

"To be clear, at no point have we been threatened with physical injury, harm or death or had a gun pointed directly at our person. At all times the guns were pointed at the ground," the crew member said.

The customs brokerage manager said he had never seen a situation in which a ship was detained and searched in such a way, "but the authorities of this country must have their motives" for doing so.

In his Friday e-mail, the crew member gave a detailed account of what had happened since the ship docked in Maracaibo on August 29.

A few hours after the ship arrived, it was boarded by officials from Interpol, Venezuelan police officers and narcotics investigators who said they had received a tip that the vessel was smuggling drugs, the crew member said.

Members of two separate agencies searched the ship, including the crew members' rooms, with dogs.