I wonder if the killer was there looking for the brother or looking for information related to the brother's whereabouts. IMO, the killer must have been looking for something.
I can envision a scenario where the killer was a "business associate" or rival of the brother, and where he showed up unexpectedly at the Lalabee's garage with an empty gas can pretending that he needed gas, tried to strike up a conversation with Ron about what Ron's brother has been up to lately and where he might be, was met with a vague, untrue, suspicious, or hostile response from Ron, and then the killer got aggressive about obtaining the info he was looking for.
The wife heard casual conversation, turning into commotion, and grabbed the knives for protection as she entered the garage to tell the man to leave their property. The presence of knives escalated the killer's aggression, and he attacked & subdued the woman (probably breaking her fingers as he wrenched the knives out of her hand), leaving her bleeding on the floor (with enough time to scrawl a desperate message in her own blood) while turning his aggression back to Ron.
I've been trying to understand what the killer was doing while Mrs. Jabalee had sufficient time to write such a painstaking message with broken fingers in her own blood, especially if the killer didn't rummage through the house at all and if the entire attack took place in the garage. I could only come up with 2 explanations: either Ron was putting up an amazing struggle for his life, or the killer was still attempting to beat Ron into giving up the information the killer wanted.
I wonder if the killer took only cash from one of the victims, or if he made off with an entire wallet (with business cards, phone numbers, etc.) or possibly a cellphone or PDA.
I apologize if this post seems insensitive to any readers out there who may have known the victims. I'm just trying to put together a scenario in my head that could explain the circumstances of the crime, and I'm doing so in the hopes that the killer will be caught and brought to justice.