A psychologist said in court yesterday that 16-year-old Lisa Ann Casella, awaiting trial on a charge of first degree murder, is having emotional problems at the Prince George's County jail and should be moved to a facility where she can receive treatment and be around people her own age. Casella is accused of hiring two teen-aged youths to kill her father.

Under Maryland law, anyone 14 or older accused of murder must be charged as an adult, but if the accused was under 16 at the time of the crime, he or she may ask the court to be tried as a juvenile. Casella was 15 when her father, Emilio Casella, was fatally s his Adelphi home on May 19.

Daniel Eric Reedy, 15, Casella's boyfriend, and Alan Fred Mozingo, 19, are alshe case. Reedy is free on bond, but is also expected to ask for a waiver to juvenile court. Mozingo is still it, Dr. Dennis Harrison, testified before Circuit Court Judge Vincent J. Femia yesterday as part of the motion by Casella's attorneys to have the case waived to juvenile court. In making such a decision, the judge must consider five factors: the age of the defendant; mental and physical condition; amenability to treatment; nature of the offense; and the effect on public safety.

Harrison described Casella as "immature, naive, gullible and dependent." He said she told him that when she was moved recently from a single cell to one with other female inmates, she became very uncomfortable. Harrison said Casella became depressed in the last month and is getting worse. He said that if she remains in an adult correctional facility, "thed emotional deterioration I have seen over the last month is going to get worse."

The short, pale, brown-hareen prison clothes, was led into the courtroom in handcuffs yesterday. She sat through the proceedings with hough her bangs. Her mother, Anna Casella, and a cousin sat quietly in the back of the courtroom. Harrison saidher mother have been in contact from time to time and that the mother visited the girl in jail last weekend. t that the only danger Lisa Casella presented was to herself. "She is nonaggressive and nonassertive," Harrisohat she had no underlying mental problems before her father's death, so "she's probably got the capacity to rebound and accept treatment more than mosI have met."

Casella's attorneys, Joseph Vallario and Joel Chasnoff, said they will present more evidence ltion that she be tried as a juvenile.