Ted Bundy pretended that he had a broken arm to lure trusting young women into his grasp. John Wayne Gacy offered promises of employment in his construction business. Charles Howard Schmid hung around high schools and impressed female students with the nice things he would buy them; once he convinced them to go out with him, some of them never returned.
To be sure, these are cleverly diabolical ways some of our infamous male serial killers have operated. But, they can't hold a candle to the masquerading ability of some of their female serial killing peers. These women successfully pretended for years to be generous landlords, caring nurses, loving spouses, or doting mothers, all the while viewing their soon-to-be-victims as pawns to be used for money, attention, or revenge. Not only did their victims suspect nothing, the people around them - friends, other family members, neighbors - were often their strongest supporters right up until the evidence was too strong to discount.
Take Helen Golay and Olga Rutterschmidt, two elderly Los Angeles ladies who would befriend homeless men, take care of them, (all the while buying multiple insurance policies on them) and then, as soon as the two year insurance payout restriction would kick in, take them out in the country and run them over until they died. How anyone could maintain a motherly facade for two years without getting the slightest bit attached to someone who has come to trust and depend on you is beyond me.
Or consider Jane Toppan. This private duty nurse used her jolly disposition and take-charge manner to gain the trust of medical staff, patients, and family members while she conducted lethal medical experiments on a doting foster sister, vulnerable elders, and sweet children.
Serial killers of both sexes present facades to gain access to their prey. What is different, though, is the ability of many female serial killers to maintain this facade over time, to plot murder while smoothing brows, and to lovingly and tirelessly nurse a spouse whom they are slowly poisoning for profit.