Rep. Chris Van Hollen (D) met with American prisoner Alan Gross in Cuba on Tuesday, the latest step in an ongoing effort by lawmakers from Maryland and elsewhere to free the former U.S. government contractor.

Gross, a Potomac resident, was detained in Cuba in 2009 while distributing computer equipment under contract with the U.S. Agency for International Development. Gross said he was helping the island’s small Jewish community gain Internet access, but Cuba accused him of trying to undermine the government and handed him a 15-year prison sentence.

Van Hollen met with Gross while on an official congressional trip to Cuba led by Sen. Patrick Leahy (D-Vt.).

Gross “was very frustrated about his continued detention,” Van Hollen said in an interview Thursday. “He was very frustrated about the fact that he is not able to see his mother who is very old and very sick.”

Gross’s mother has undergone chemotherapy as she battles cancer. Gross has suffered some health problems of his own while in prison, and his wife, Judy Gross, has called for him to be released on humanitarian grounds. The Cuban government has disputed the notion that his health is at risk.

“He was very thin. He showed me all these extra holes he’d hand to punch in his belt because of his weight,” Van Hollen said.

Van Hollen added that Gross is so eager to see his mother that “he was very adamant about the fact that he would return to Cuba” to serve out his prison sentence if given the chance to visit her.

Van Hollen said he raised the issue of Gross’s detention directly with Cuban President Raul Castro when they met, but “his response was to raise other issues” — a suggestion that Cuba views Gross as a possible bargaining chip in broader negotiations between the two countries.

Van Hollen said he and the other lawmakers on the trip were of the belief that relations between the U.S. and Cuba need to thaw and evolve. But, he said, “the continued detention of Alan Gross is an obstacle to moving forward.”