Staining for iron showed previously overlooked intra-alveolar siderophages widely distributed in the lungs of two pairs of siblings, all of whom had hospital admissions for apparent life-threatening events (ALTEs) before dying suddenly at home. A mother and babysitter were convicted of their murder and manslaughter respectively. There were no siderophages in the lungs of a fifth infant whose death was included in the murder charge but who had no ALTEs. Bleeding from mouth or nose was observed during six of ten previous ALTEs suffered by these children and three unrelated infants in the same care. Such external hemorrhage is well described in imposed infant suffocation which may be one aspect of "Munchausen syndrome by proxy" child abuse. Our findings imply that there may also be intrapulmonary hemorrhage and that intra-alveolar siderophages can be a marker for previous abuse. Retrospectively we found diffusely distributed intra-alveolar siderophages in the lungs of seven of 158 infants with diagnoses of SIDS. Siderophages in such numbers demand an explanation and if this is not provided by clinical history or other necropsy findings should cause suspicion of previous imposed suffocation and infanticide and require further enquiry. The lungs should be stained for iron in all cases of sudden infant death.