I don't believe the new maid's arrival had anything to do with what happened, really. IMO, the poor woman was just in the wrong place at the wrong time.
I believe, and this is just my opinion of course, that LS had become very frustrated with the situation over little Josef, and perhaps Viktoria's disinclination to give a straight answer. They quarrelled about it, obviously not for the first time, and a meeting/assignation was arranged for that evening, in the barn. An argument blew up and LS strangled Viktoria in a rage, after attacking her.
It may have been that her mother came to the barn to see what was going on and was attacked/strangled in her turn. LS disliked the family and probably decided he wasn't going to be executed for murder if he could help it and after killing Viktoria he would certainly be suspect number one.
Therefore, the whole family had to go, though I think he had regrets that Josef had to die. Nevertheless, he did it and then covered his tracks afterwards in order that the bodies not be found before he intended them to be. He was successful at that enterprise as it turned out though he may not have been if the police had been extremely efficient.
This is an extremely plausible theory!
The only thing I wonder, though, is: had he actually been planning this a while? I think the 'strange happenings' was a part of it, rather than a spectacular series of coincidences.
Apparently, just the day before the murders, Gruber noticed that someone had tried to break into the garage attached to the house - but who stated this originally is something else I must check.
What I don't get is, if some mysterious creeper had access to the attic (which covered the whole L-shaped farmhouse) and made noises up there for six months, at least, prior, why'd they need to break onto the garage at all?
Idk, I think this wasn't entirely a spur of the moment crime. But I agree with you mostly, especially about Viktoria being strangled, and the rest probably following on from there.
Yes, if it is LS relaying all this to others after the homicides about Gruber stating that there were mysterious noises, footsteps in the snow etc, then that adds further suspicion to him, IMO. This is especially true if he was the originator of the story of the attempted picked lock of the tool shed.
On the other hand, the Grubers' former maid was apparently convinced that the farmhouse was haunted so she must have heard strange noises, footprints etc too.
Perhaps, out of sheer maliciousness LS was on a scare campaign. After all, he didn't get on with any of them, at all really, even Viktoria.
It may have appealed to a person with a rather strange black sense of humour to attempt 'a haunting'.
Was the mattock accidentally left out in the barn on that particular evening I wonder?
Or it could have been a spur of the moment murder like Rosella has said. LS could have strangled,or tried to strangle Vickoria in an argument. She ran away and he bludgoned her to death. The Father and Mother could have entered the barn because they heard the screams from Vicktoria. The little girl could have followed them. LS would then have had to kill them all.
When he went into the house, he may have been surprised by the new maid that he did not know had arrived. He had to kill her. The little boy may have watched, and so he had to kill him too.
In trying to work out a get out of jail free card he may have remembered the previous maid's story about the haunting, and elaborated on it, while he was establishing his alibi, and keeping the smoke coming out of the chimney and the cattle fed.
Little Josef was sleeping in some sort of bassinet/cot arrangement ? Was he in a pram, as if Viktoria had taken him somewhere? Perhaps she was going to put him into bed later. I take it he was killed in his mother's room?
I -think-there was a proper cot in the main bedroom, but Josef was in his hooded stroller in the maid's room. Good point, perhaps they'd all been out for a walk - maybe Viktoria and Cazilia hadn't time to change into bed clothes like the rest. There was something about cows wandering loose, too... that's another part of the original docs that's very hard to read through Google translate, which has "unleashed beef" in the yard, for goodness' sake.
I'm actually going to work up a timeline of 'odd events' and who witnessed/reported them, when I get the time. I think this might be quite revealing, if LS indeed elaborated on them for the sake of an alibi.
Oh, another thing that gets me is.. LS swore up and down, while admitting to sleeping with Viktoria, that he'd done so only five times, and only because she basically forced him!! Pull the other one!
Something else that needs to be clarified I think. With all the family dead who would the farm have legally gone to. It belonged to the daughter, with her dead would it have gone to her son, who was also killed? In that circumstance would LS have any claim as his alleged father?
Hatchett, the post I quoted in that link clears all that up. It made me wonder if the suspect pool should be expanded to include greedy relatives. It's a bit Hollywood, I know.. but what if the 'haunting' and other weird events were designed to run Gruber off the property, and when that didn't work, they were simply all killed.
Personally, I'm more convinced LS did it. But worth a thought. Anyway, whoever got the farm got the raw end of it, didn't they.
Hatchett, I'm happy it was posted too. Glad to help in bring info over from WS & elsewhere.
These very old, very cold 'mysteries' are a passion of mine.. I tend to obsess on a different one every couple of years, this one's a quite recent one to me so I haven't really delved yet, just c&p'ing and running stuff through translate. But I'm glad it's been useful.
Off topic: If anyone's interested in other strange older crimes, one of the ones myself and fellow sleuthers went to town on was the Elfrieda Knaack case, incredibly strange and intriguing.. with a weird spiritualism cult, one or two degrees of separation from Charlie Chaplin, John Dillinger, Frank Lloyd Wright and other notables of the era. Plus, one of the most puzzling deaths I've ever come across!