The jury in the D.C. Superior Court murder trial of Paul Leon Jordan heard testimony yesterday backing two key defense contentions -- from a psychiatrist who said Jordan suffered from a severe alcohol problem that can lead people to invent false stories, and from the sister and friends of the slain woman, who raised questions about the victim's alleged affair with Jordan.

A sister and two friends of Cora Barnes, who was stabbed to death last Jan. 24 along with 3-year-old Crystin Fletcher, testified that they had never seen Jordan, a former neighbor of Barnes, at the Barnes home.

Later, forensic psychiatrist Neil Blumberg testified that Jordan was suffering from alcohol withdrawal the day he confessed to the killings -- a condition he said may be marked by the invention of events that did not occur.

According to police testimony and a videotaped statement, Jordan, a 48-year-old alcoholic, said he killed both victims after Crystin's cries interrupted his lovemaking with Barnes, the child's babysitter.

Jordan, according to the testimony, acknowledged having a long affair with Barnes, who was 56 and lived next door to him at 4321 Second St. NW.

The affair is a key element of the government's case.

But defense attorney Penny Marshall asserted in opening arguments that "there was no affair . . . no motive, no opportunity. Mr. Jordan did not commit these murders." She argued that Jordan, suffering from severe alcohol withdrawal, was psychologically coerced by police into confessing "to a crime he did not do."

Yesterday the defense began presenting its case in the nearly three-week-old trial as Blumberg, who has interviewed Jordan and studied his medical history, gave jurors a lesson in the symptoms of alcohol withdrawal and portrayed Jordan as a man with a severe alcohol problem.

At one point, defense attorney James H. McComas asked Blumberg to assume that Jordan's statement about his affair with Barnes, in which Jordan said they drank, watched soap operas and made love, "was false." What, McComas asked, was the doctor's medical interpretation?

Blumberg replied that it was an example of a withdrawal symptom in which a person "invents information that may not be true. They believe it really happened."

Blumberg testified that in an interview last September, Jordan described the relationship with Jordan's wife "in the exact same terms as the relationship with Cora Barnes . . . . What appears to have happened during the police interview is he transposed those events and said he had that relationship with Cora Barnes."

Blumberg also testified that Jordan has had an alcohol problem for 25 years -- one that has led to "blackouts, tremors, seizures and delirium tremens," a severe form of alcohol withdrawal that can be fatal.

Jordan has been hospitalized three times since 1977, hospitalizations marked with bouts of hallucinations and, in one case, complaints of "hearing voices making accusations about him," Blumberg said.

Jordan was taken to D.C. General Hospital by police at about 2 a.m. Feb. 15, the morning after he was arrested and questioned for hours and then confessed.

According to Blumberg's testimony, Jordan was "well within the alcohol delirium spectrum" when he was he was taken to the emergency room.

The psychiatrist also testified that Jordan, when suffering from withdrawal, was in a "highly suggestible state . . . more susceptible to being influenced."

The defense has contended that Jordan was influenced by leading questions and outright lies during questioning by police.

Blumberg's testimony for the defense was scheduled to continue Tuesday, when prosecutor Amy S. Berman will have a chance to cross-examine him.

Also during yesterday's proceedings, Barnes' sister, Alease Brooks, and two women who were friends of Barnes testified that they had never seen Jordan at Barnes' home when they visited.

On cross-examination, the two friends acknowledged that Barnes kept to herself about her personal life.

One friend also acknowledged that she never visited Barnes during the afternoon, and the second said she seldom visited her at that time.

According to previous trial testimony, Jordan visited Barnes during the afternoon hours.