MARYVILLE, Tenn. (WVLT) -- The mother of fallen Maryville Marine has left on her own mission: to keep her family together.

Robin Ferschke is set to speak at an immigration rally in Washington D.C. Tuesday.

"This has to be done for my son to honor my son and his family," Robin Ferschke said before boarding a flight at McGhee Tyson Airport.

Ferschke's son, Sergeant Michael Ferschke Jr., was killed while serving in Iraq in August 2008.

The Ferschke family has been caught in a bureaucratic battle ever since. Immigration laws don't recognize Sergeant Ferschke's marriage to his Japanese widow, Hota.

She could be prohibited from living with the Ferschke family in the United States in just months.

Robin Ferschke, Hota Nakama Ferschke, and nine-month-old Mikey Ferschke left for Washington D-C Monday morning.

"I think this is what I need to do to honor my husband," Hota said. "I promised my husband to raise our son in the United States.

Sergeant Ferschke married his Japanese bride by paper-proxy while serving in Iraq, after the couple learned Hota was pregnant.

Sergeant Ferschke died a month a later. A decades old U S immigration law doesn't call the union legitimate.

"The 1952 law says they have to consummate after marriage in order for her to be married in the United States. They couldn't consummate because my son never came back," Robin said.

The Ferschke's are caught in a race against time. Hota's visa expires in January.

Robin and Hota are scheduled to speak at the U.S. Capitol and meet with lawmakers.

"[I'm] Extremely nervous. I just hope I can do it, but I know my son is up there giving me strength to do this," Robin said.

Because like her son, she knows her mission and won't give up.

"I won't stop. I won't stop fighting," Robin said.

Congressman Jimmy Duncan has introduced a private bill that would allow Hota Ferschke to live in East Tennessee.

The bill is still in a house subcommittee.