Stain raises numerous possibilities in Martin case
By Alex Wood
Although the physical evidence currently available in Manchester’s Bernice Martin rape-murder case neither identifies Richard Lapointe as her assailant nor rules him out, there is one piece of evidence that some observers have found compelling. Analysis Scientists could find no sperm, or male reproductive cells, in a semen stain found on Martin’s bedspread after the March 8, 1987, crime. And, after the birth of his son a number of years earlier, Lapointe had undergone a vasectomy, an operation that prevents a man from emitting sperm. But that evidence becomes somewhat less compelling when examined more closely: Vasectomies are not uncommon; there are other reasons why a man can be unable to produce sperm; any man can, under certain conditions, produce semen without sperm in it; and at least some forensic scientists say they often have difficulty finding sperm in semen samples. Examination of such issues remains relevant because some of Lapointe’s supporters argue that there is substantial reason to believe he is innocent of the murder, despite his 1992 conviction. Lapointe, who was born with brain abnormalities that went untreated until he was 15 years old, may have confessed falsely due to intense psychological pressures placed on him during a Manchester police interrogation lasting more than nine hours, they contend. While Lapointe obviously isn’t the only man who ever had a vasectomy, no evidence was presented at his trial on just how common vasectomies are. Researchers at the National Center for Health Statistics in Hyattsville, Md., have estimated that, as of 1987, about one in six men from ages 37 to 84 in the United States had undergone vasectomies, according to Christine S. Cox, a statistician at the center. And a vasectomy isn’t the only reason a man’s semen can lack sperm. According to a 1977 forensic medicine textbook, edited by C.G. Tedeschi and associates, such men may include “the very old, the very young, and those suffering from a variety of diseases,” including testicular cancer and tuberculosis – as well as those men who have had mumps or untreated gonorrhea. Although the number of sperm in normal semen is astronomical – 400 million to 600 million in an ejaculation, according to Tedeschi’s book – they aren’t evenly distributed. “The bulk of the spermatozoa are carried in the first half of the emission, so a stain caused by the terminal drops of a healthy ejaculate may contain few spermatozoa,” say Francis E. Camps and J.M. Cameron, both of London University, in a 1971 textbook, “Practical Forensic Medicine.” So, for example, if the forward part of the ejaculate apparently left by Martin’s killer went on his shirt, the part left on the bedspread would be expected to have few sperm. “It is quite unsafe to conclude that absence of spermatozoa from a seminal stain means it came from a man whose ejaculate is abnormal,” Camps and Cameron write. Moreover, Tedeschi’s book says, “the seminal fluid of a healthy young man may be completely devoid of spermatozoa if he has experienced numerous ejaculations over a relatively short space of time.” So, if Martin’s killer ejaculated repeatedly into his clothing or onto some material that wasn’t recovered, that too could account for the lack of sperm in the sample. Some scientists say it is frequently difficult to find sperm in semen stains – though other scientists disagree on this point. Beryl Novitch, a lead criminalist at Connecticut’s state police forensic science laboratory, did initial tests on the semen sample found in Martin’s apartment, including unsuccessful attempts to find sperm by examining some of the material under a microscope. But she testified at Lapointe’s trial that she “very often” is unable to find sperm in semen stains. And John Coleman, who found no sperm while trying to test the remainder of the semen sample for DNA at Lifecodes Corp., also testified that it is “not unusual” to be unable to find sperm or DNA in semen stains. Lawrence Kobilinsky, assistant provost at the City University of New York’s John Jay College of Criminal Justice, says analysts often are lucky to find one or two sperm cells in a large semen stain. It’s not unusual to find none, he adds. The search can be complicated by the type of material that is stained. For example, Kobilinsky says, he always has had difficulty finding sperm on jeans. He suspects the reason may have to do with the type of dye used in jeans. But Barbara K. Caraballo, supervisor of blood studies at the Palm Beach, Fla., sheriff’s office laboratory, estimated in an interview that less than 2 or 3 percent of the semen stains she sees lack sperm. And Robert C. Shaler, director of forensic biology in the chief medical examiner’s office in New York City, estimated the figure at 5 to 10 percent. When a reporter described to Caraballo the techniques that researchers used to look for sperm in the Lapointe case, she said, “Everything you’re telling me indicates there was no sperm. If sperm was there they would have found it.” Coleman testified at Lapointe’s trial that heat can degrade sperm and DNA. Some of Lapointe’s supporters have seized on that testimony as an explanation for why the semen sample might have lacked sperm. They argue that the sperm might have been destroyed by heat from the fires set in Martin’s apartment during the crime. But Caraballo expressed skepticism about that theory. The stain found on Martin’s bedspread was identified as semen through chemical testing, and Novitch was able to determine that the person who deposited it had type A blood. Caraballo said heat would have degraded the chemicals detected in those tests before destroying the sperm and DNA.