Police in Boston and the local district attorney’s office recently defended their decision to hand over a possibly faulty ventilator to the manufacturer to let it examine the device that shut down during a power outage and led to the death of a 15-year-old. There is serious concern that sending it back to the manufacturer, Pulmonetic, without any independent oversight could result in evidence not being preserved or possible destroyed. The machine appears to be one of more than 10,000 machines that were recalled by the company in 2004 because of the potential for the backup battery to fail.