The 46-year-old man on death row for fatally stabbing an elderly Baton Rouge couple on New Year’s Day 1991 falls within the borderline intelligence range but is not mentally retarded, a court-appointed expert testified Tuesday.
Psychologist Curtis Vincent’s testimony in the 19th Judicial District Courthouse came five months after a psychologist hired by Allen “Lil Boo” Robertson Jr.’s attorneys testified that Robertson is mildly mentally retarded.
“My professional opinion ... is that I don’t believe he meets the criteria for intellectual disability,” Vincent, of Baton Rouge, said of Robertson.
Intellectual disability is the term now used by mental health professionals to describe mental retardation.
East Baton Rouge Parish prosecutors contend Robertson, of Baton Rouge, is not mentally retarded and can be executed for killing Morris Prestenback, 76, and his wife, Kazuko, 71, in their Dalton Street home.
Robertson’s attorneys claim he is mentally retarded and therefore not eligible to be put to death.
The U.S. Supreme Court ruled in 2002 — seven years after Robertson was convicted and condemned to die for a second time in the case — that the mentally retarded cannot be executed.
The mental retardation hearing is scheduled to conclude Wednesday, after which state District Judge Mike Erwin — who presided over Robertson’s 1991 and 1995 trials — will issue a ruling.
Dr. Mark Cunningham, the defense’s expert psychologist, testified in November that Robertson’s IQ testing over the years produced scores of 76 in 1984, 74 in 1995, 66 in 2008 and 73 in 2012 — for an average of 72.5. Cunningham put Robertson’s mental retardation in the mild range.
Vincent testified Tuesday he places Robertson in the borderline intelligence range, which he said covers IQ scores from 71 to 84.
Assistant District Attorney Prem Burns, who prosecuted Robertson, noted there is no mental retardation diagnosis in Robertson’s school records.
He was expelled in the eighth grade.
An IQ of 70 is generally held by courts as the threshold to measure mental retardation, although other factors — such as a person’s ability to function in society — also are considered.
Vincent testified Robertson’s considerable alcohol and drug use by the age of 11 likely contributed to his low academic performance, as did a lack of motivation and supervision at home. Robertson’s mother drank heavily, Vincent added.
“It’s a horrible environment to grow up in,” he acknowledged.
Vincent said he interviewed Robertson on death row and found that he used high-level words and sentence structure, knew income taxes are paid in April, understood the purpose of a will, and showed he could pay bills.
The Louisiana Supreme Court overturned Robertson’s first conviction and sentence in 1994 because of a jury-selection problem.
Robertson was again found guilty and condemned to die in May 1995. The state high court affirmed that conviction and sentence in 1998.
Burns argued at both trials that Robertson, who was 23 at the time of the murders, killed the Prestenbacks while burglarizing their home for money to buy drugs. The frenzied attack left blood spattered on walls, bedclothes and ceilings.