If you accept that Patsy wrote the note, then there was no intruder

What I find compelling about this case is something so simple. Several handwriting experts said Patsy wrote the note. It was written on her pad, with her pen, with her fingerprints on it. Not a single expert said she did not write it. There was only one who said they couldn't say for sure but also said she couldn't be ruled out. Meanwhile, they ruled out John Ramsey. And Don Foster, an esteemed linguistic expert who looks at not just lettering but syntax and language, said this (from Steve Thomas' book):

Don Foster from Vassar, the top linguistics man in the country, made his conclusion firm in March. “In my opinion, it is not possible that any individual except Patsy Ramsey wrote the ransom note,” he told a special briefing in Boulder, adding that she had been unassisted in writing it.

Steve Thomas; description of Foster:

Foster had the look of a mild professor, but if I were a criminal, I wouldn’t want him after me. When only a University of California graduate student in 1984, he found an elegy to a murdered actor, “the late Vertuous Maister William Peter of Whipton neere Excster,” and after several years of painstaking work, proved it to be a lost work of William Shakespeare from the year 1612. Anyone that dedicated tends to finish what he starts.

Since discovering the Bard’s elegy, Foster had refined his techniques and made the news again when he unmasked the anonymous author of the highly publicized book Primary Colors. That led the FBI to use him to identify the Unabomber as Theodore Kaczynski. These days Foster’s telephone was ringing off the hook as police and the corporate world sought his singular expertise in textual analysis. He was the best in the country at what he did.

He explained that his work was based on much more than just one letter looking like another. Even the slightest things, such as the use of periods or the space before the start of a paragraph, could create a distinctive linguistic fingerprint. After all, it was the unconventional use of commas that had spurred his original theory about the Shakespeare fragment. “We can’t falsify who we are,” Foster told me.

“Sentence structure, word usage, and identifying features can be a signature.” Throughout the month, I furnished Foster with a wide range of material from a number of suspects so we would not be accused of stacking the deck. One of the first things he picked up on was Patsy’s habit of using acronyms and acrostics in her communications. She often signed off with her initials, PAPR, and used such phrases as “To BVFMFA from PPRBSJ,” which meant, “To Barbara V. Fernie, Master of Fine Arts, from Patricia Paugh Ramsey, Bachelor of Science in Journalism.” That, I thought, might somehow link to the mysterious SBTC acronym on the ransom.

James Kolar's description of Foster:

... he discovered the identity of the author who anonymously wrote the highly publicized book, Primary Colors. Foster utilized a computer program to search for similarities of the sentence structure and phrases used in the book and compared them to the known writings of other individuals. Newsweek columnist Joe Klein’s published writings stood out, and Foster identified Klein as the anonymous author of the work.

The textual analysis and syntax discovered over the course of the computer search revealed Klein’s favored use of adjectives like “lugubrious” and “puckish.” More specifically, Foster discovered that Klein had used the phrase “tarmac-hopping” in both a column and in Primary Colors.8 It took Klein 6 months of denial before he finally admitted to authoring the book.

So to me, step one of this case is the note. Everything else builds upon it. If she wrote the note, then she and John are implicated in the crime and cover-up. There is no other option.

Why the DA would continue to pursue the intruder theory when it was pretty darned obvious that Patsy wrote the note is beyond me. It suggests that they simply did not want the Ramseys to be culpable for this crime. And yes, it also makes me wonder: if this was middle class John and Jane Doe and not wealthy John and Patsy Ramsey, would one or both of them have been arrested after the first few days or maybe even that day?