The trial for the Egyptian grandmother accused of abducting her two grandsons from their home in Maryland to her residence in Cairo opened Tuesday with their father on the witness stand.

Michael Shannon, who had full custody of his older son when the boys were taken in August 2001 and has since been granted custody of 2-year-old Jason, was the first and only witness to testify Tuesday in the case of Maryland v. Afaf Nassar Khalifa.

"I haven't seen my boys in 72 weeks," Shannon, 42, told State's Attorney Laura Kiessling on the stand.

The state is arguing that the wealthy Khalifa and her daughter, Nermeen Shannon -- the boys' mother and Michael Shannon's ex-wife -- kidnapped the children in August 2001 during a court-approved, unsupervised visit that was only supposed to last a week, and flew them from New York to Egypt. Michael hasn't seen the boys since, despite several court orders to return them home.

"Her [Nermeen's] mother was part and parcel of the plan to take the children," said Kiessling in her opening statement. "Michael could not find out. Michael had no idea."

Khalifa -- who waived her right to a jury trial in favor of a trial-by-judge at Anne Arundel County Circuit Court -- has been charged with 15 felony counts related only to the alleged kidnapping of Adam, 5. If convicted Khalifa, 60, could face up to 20 years in prison.

When the boys were taken, the Shannons had a consent agreement stating that Michael had full custody of Adam and Nermeen had full custody of Jason.

During the couple's divorce hearing the month after the boys disappeared, the courts also granted custody of Jason to Michael, citing previous charges brought against Nermeen for child abuse. Mrs. Shannon also struggles with alcoholism, according to testimony.

Mr. Shannon said he only gave Khalifa permission to take the children to Brooklyn, N.Y., for a weekend to see relatives and insisted that Adam and Jason be back to his house by 6 p.m. Sunday. Khalifa agreed to the plan, he said.

"She swore on Allah, her children's eyeballs and her family's health that she would have them back," Mr. Shannon said.

When the boys weren't returned as promised Sunday evening and his calls to Khalifa and Mrs. Shannon went unanswered, he went to his ex-wife's apartment to find that most of the furniture and belongings had been removed, he testified.

"The apartment was empty, cleaned out," he said. "So I called 911."

He gave statements to police that night but told defense attorney William C. Brennan during cross-examination -- which was still going on when court adjourned Tuesday -- that he couldn't recall most of what he'd said because he was so upset.

The following day he was able to reach Khalifa at her home in Cairo, but she told him to talk to her husband, according to testimony. All his requests to have the boys returned have been denied, Mr. Shannon testified.

Brennan didn't make an opening statement, and his defense strategy wasn't entirely clear from his line of questioning -- much of which seemed aimed at rattling Mr. Shannon and casting doubt on his credibility.

Brennan asked him whether he'd ever been told that Khalifa and her daughter wanted to take the boys to Egypt for two weeks to discuss the distribution of their sick grandfather's property and assets. Shannon replied, "Never."

At one point, Brennan produced e-mails Mr. Shannon had sent to his former sisters-in-law, and Mr. Shannon admitted that some of what he'd written in them about the situation with his sons wasn't true. He said he lied to them because they routinely lied to him.

Brennan asked him if he often made things up.

"Not if I'm under oath," he replied.

Michael testified that his ex-wife told him her mother abducted the children because she and her husband, Osama Khalifa, have only daughters and wanted male heirs.

Afaf Khalifa was first arrested early last summer in California, where her family has a residence, on kidnapping charges, but was released on bail. She was arrested again in July, jailed and extradited a short while later to Maryland for trial.

Foxnews.com broke the story in early July, before Khalifa's second arrest.

"It's been a nightmare," Shannon said then. "I am doing everything I can legally to get them back."

Khalifa declined to comment on the case Tuesday, referring questions to her attorney.

Kiessling and Brennan said they couldn't discuss the trial while it was in progress. Court proceedings are expected to last through the week.

International kidnappings of children by a parent are fairly common, with at least 10,000 confirmed cases of abducted American children overseas. Shannon's case is unusual because it's a father, not a mother, who has been left behind.