So this ought to start you off with a little taste...
From the Austin Daily Statesman, January 1, 1885, comes the first of many news reports abut the serial killings that were to be attributed the "Servant Girl Annihilator" (or "Annihilators"). The body of Mollie Smith, a "light-colored mulatto" about 25 years old, was found "nearly nude" by an outhouse roughly fifty paces outside the bedroom where she had been sleeping with her commonlaw husband, Walter Spencer. The assailants — and there were probably two here — first bashed poor Spencer's face in with some kind of heavy object, either a brick or metal pipe. Mollie was then dragged outside; she apparently put up a heroic struggle, but she wasn't heard to scream (there were other people asleep in the same house). This indicates the assailant probably was covering her mouth while dragging her outside. Spencer came to some time later, noticed Mollie missing, went for medical help himself (his facial bones had been cracked up pretty good by the blows), but didn't find Mollie's body until the morning.
A number of interesting questions about this event. For one thing, a bloody axe was found on the floor by Mollie and Spencer's bed. Since Mollie was still alive when she was being dragged out of the house, she wasn't killed until she had been taken out by the outhouse. Where she was killed...with an axe. (One out-of-town newspaper reports she was so hacked up her body was falling to pieces as it was being lifted into a casket, but that can't be confirmed and is probably an example of the kinds of lurid reporting you see in Victorian era newspapers.)
This suggests the killer either went back inside to leave the axe on purpose, or, perhaps, went back inside to do something else (subdue another victim? look for valuables?) and left it behind either uncaringly or accidentally. But moreover, it strongly suggests two assailants. Spencer was not hit with the axe but some other object. The axe had definitely been brought to the scene by the assailants; everyone living at the house testified no one there owned an axe. So whatever the other object was that struck Spencer, it must have been brought and taken away, since there were no reports of another bloody weapon on the scene. So, if there were only one assailant that night, we're left with the spectacle of a man dragging the thrashing, panicked Mollie outside while covering her mouth to stifle her screams, and simultaneously schlepping a big axe and whatever he hit Spencer with. Seems implausible. Two men that evening are more likely.
Spencer recovered, only to be arrested as a suspect then released. (No one really thought he did this or any of the subsequent murders.) There were other arrests, other suspects, and more ghastly killings to come.