By Allison Klein and Elissa Silverman
Washington Post Staff Writers
Saturday, June 7, 2008

A woman whose body was found floating in the Potomac River on Wednesday is thought to have committed suicide, a source familiar with the investigation said.

Helen Johnstone, 47, who lived in the 4800 block of MacArthur Boulevard NW, was discovered about 1 p.m. near Georgetown, according to D.C. police. Drowning is the probable cause of death, said the source, who declined to be identified because the investigation is continuing. The D.C. medical examiner's office has not declared an official cause and manner of death.

Divers pulled Johnstone from the water near Jack's Boat House, in the 3500 block of Water Street NW. Investigators said they do not know where she entered the water, the temperature of which was estimated at 55 to 60 degrees. Her body had minor injuries, police said.

Johnstone's body was discovered by Lynda Carter, the actress who portrayed Wonder Woman in the 1970s television series based on the comic book character. In a telephone interview, Carter said she was alone in a boat when she saw the body.

Carter said she did not have a cellphone with her and did not see other boats in the water, so she yelled to some fishermen to call police. She said she waited until rescue boats arrived and directed them to the body.

"I didn't do anything special," Carter said. "I did what anybody would have done."

Johnstone's family owns a well-known sailboat manufacturing company, J/Boats, which is in Rhode Island.

Staff writer Del Quentin Wilber and researcher Meg Smith contributed to this report.