To the naked eye, the white cloth appeared clean, save for a faint yellow outline that could easily be overlooked.
The forensic nurse removed a pair of tinted glasses from a sanitizing bag. As the hum of the machine filled the exam room, she turned off the lights. By shining rays of violet, blue and green light, she could see that a foreign fluid was present.
The alternative light source, known as ALS, has been used at Mercy Medical Center for years in sexual assault cases, giving investigators the means to detect the presence of bodily fluids on skin and clothing.
But now, the machine is being used more frequently in domestic violence cases that involve strangulation — a crime that previously had been difficult to prove.
The technology now being used at Mercy has not only given doctors a strong tool to aid victims, it's given police a powerful means to go after the attackers. And the more investigators learn about the machine, the more mainstream its use is becoming in domestic violence cases.
By just turning a dial and projecting different colors of light on the skin, "you can detect the extent of the strangulation; you can even see handprints around a victim's neck," said Lt. Vernell Shaheed, the recently retired commander of the family crimes unit of the city Police Department.
Nearly half the cases that go through the family felony violence division of the state's attorney's office involve strangulation, and that number is on the rise. The new technology means that more suspects can be charged with an offense, or a more serious offense.
Until recently, the four-year-old machine had been used only to detect fluids in sexual assault cases. But using the same technology, forensic nurses are able to reveal pooled blood beneath the skin on domestic violence victims. Because of its cost, however, only Mercy and one other hospital in Maryland have such a machine.
The increased use can help uncover more cases of strangulation. Without ALS, there is often little evidence of a crime. Ninety-seven percent of strangulation victims have no visible marks, according to Debra Holbrook, a forensic nurse at Mercy Medical Center
As a result of ALS, first-degree assault charges were brought in 62 cases last year, up from 16 in 2005. Prosecutors said most of the victims in those cases were evaluated with the ALS.
"Thanks to ALS we're keeping more cases," said Julie Drake, head of the family felony violence division of the state's attorney's office. "Before, there was no way we could argue a first-degree assault; we couldn't prove it in court. Now we can."
However, no case in which ALS was used has been presented to a jury; most charges result in guilty pleas from the defendants, Drake said.
The technology, a small black box with a handle and lens, works by projecting blue, green and violet light waves that can reveal what's beneath the skin, such as pools of blood. The technology is also used to detect fluids on a victim's skin, such as water, saliva and semen, and is commonly used in sexual assault cases.
In many strangulation cases, victims show no outward signs they are in trouble. Internal swelling can kill victims within two hours and clotting caused by strangulation can lead to strokes as long as two years after the fact, according to Shaheed.
"Victims can have a sore throat or difficulty swallowing, and have no idea the danger they're in," she said.
But DeVera Gilden, a social worker in the police's family crimes unit, said many in the department and in the court ststem still do not see strangulation as a serious offense, and Lilly said that many police officers do not take advantage of the technology in domestic violence cases.
She said there is an effort to educate those in the system about the potentially deadly impacts of strangulation, including an educational video for judges.
There is a push for stronger legislation in Maryland in hopes that the crime will be taken more seriously.
She pointed to other states that have pushed to get steeper punishment for strangulation crimes — even if ALS technology isn't routinely used.
New Hampshire and Connecticut, for example, have passed stronger laws create harsher penalties for strangulation.
"We're trying to raise awareness and get the message to abusers that strangulation is a crime and you can't get away with it anymore," said Beth Rodd, a New Hampshire lawmaker who co-sponsored that state's bill. "You'll get abusers who say 'You can't do anything about it — there are no marks.' "
In Maryland, Gilden and other advocates say ALS may change that in more cases.