On the premise that Galatians was written after Paul's first missionary journey, when he visited the lower region of the province of Galatia (Acts 14), but before the Jerusalem Council (Acts 15):

To what "prior writing" (proegraphē) was Paul referring in Galatians 3:1 which speaks of Christ as crucified?

>You foolish Galatians, who has bewitched you, before whose eyes Jesus Christ was publicly portrayed (proegraphē) as crucified? (Galatians 3:1 NASB95)

English Bibles consistently translate proegraphē as "publicly portrayed" in Galatians 3:1, but this is inconsistent with how the various forms of prographō are translated in the rest of the New Testament, although some may take Jude 4 as referring to a figurative prior writing. Further, the instances of this word which I've assessed in the LXX and in Greco-Roman writings can all be understood as referring to something which is previously written, painted, etc., including those instances where something is "set forth as a public notice," per the LSJ lexicon. Although, admittedly, some instances are ambiguous. [If you are aware of an instance where the word definitely does not refer to something which was previously written, then please let me know! I address a number of Greco-Roman uses of the word in my book: https://atrustworthygospel.com/the-book-is-now-available/]

Note: the stated premise about the timing of the letter to the Galatians is asserted by Bruce, Lonenecker, and Schreiner. I can provide proper footnotes, if desired.

4/21/24 Update: I remain interested in any proposed "prior writings" to which Galatians 3:1 might be referring.

I recognize that BDAG has classified this instance of *proegraphē* under the "to set forth as a public notice" bucket, despite Paul using *prographō* forms elsewhere to refer to prior documents, whether his own or the OT. I recognize that many commentators are quite happy to treat this instance in a metaphorical or figurative "public notice" sense as referring to Paul's oral presentation, despite there being no other Greco-Roman examples per my research where the term refers to a strictly oral presentation. I recognize that some commentators float the idea that Paul may be referring to the placard affixed above Jesus on the cross, without explaining how this placard was put before the eyes of the Galatians and how the placard itself presents Christ as crucified.

Nevertheless, on the premise that we should first try and translate NT words according to their more common usages and consistent with how an author uses the word elsewhere, unless context requires otherwise, I want to pursue the question as originally asked. The only "prior writing" that I can envision Paul as possibly sharing with the Galatians is something akin to an early Gospel. Are there other "prior writing" options, such as something in the OT? 

Thanks.