Also, re: annulments--there is a difference between a civil (government) annulment and a canonical (Catholic church) annulment. A marriage is essentially a government-sanctioned contract, but the issue gets muddled because the US is one of the few countries where a religious ceremony is allowed to substitute for a government ceremony (in many countries, you have to have the government ceremony, and then you can have a religious ceremony in addition if you wish). So you don't have to be Catholic to have a marriage annulled (and getting a civil annulment doesn't mean you automatically get a Catholic annulment, or vice-versa--they're two separate things, and two separate "courts"). Even for a Catholic, you don't have to have a marriage annulled--you just have to have to have the marriage annulled if you want to marry again in a Catholic church (or if you're a previously married non-Catholic and want to marry a Catholic in a Catholic wedding). If a divorced Catholic wants to marry a second or third time in front of a Justice of the Peace, that's fine as far as the government is concerned. It's just not fine in the eyes of the Church.
Also, "non-consummation" isn't the only grounds for an annulment (although it's the one we think of most); you can also get an annulment (both civil and Catholic) for a variety of reasons, such as incompetency or fraud, or finding out you're closely related. Whenever you read about celebrities who get wasted and then have a quickie Vegas ceremony, and then get an even quicker annulment (Carmen Electra & Dennis Rodman, one of Brittany Spears' marriages pop to mind), it's on the grounds that they weren't in their right mind enough to understand the gravity of what they were doing, and they're getting a civil annulment (since you can't get have a quickie Vegas wedding in a Catholic church, since you generally have to slog through months of pre-Cana first).
The Catholic Church has seriously eased up on granting annulments quite a bit in the last 10 or 20 years or so, but at the time Marci disappeared, a Catholic annulment would have been much more difficult to get. And even a civil annulment is generally more difficult to get than to just get a divorce. So I'm a little surprised that Marci's husband went as far as getting an annulment. I can only think of a few reasons that might be: 1. they were staunch Catholics; 2. he wanted to marry again quickly, and didn't want to wait however long you have to wait to prove "abandonment"; 3. he re-married (quickly or not) to a staunchly Catholic woman; or 4. there was some financial benefit to filing for annulment vs. divorce. (Of course, that would depend on the Washington state divorce laws at the time.) Children born from an annulled marriage are still considered "legitimate" both civilly and in the Church, so that probably didn't have any bearing on choosing annulment over divorce. (Arguing that "this will make the kids illegitimate" might be an emotional tactic used to fight a partner about an annulment, but it doesn't have any legal or Church grounds. At least, it doesn't matter unless you're in line for the throne.)
It would be interesting to know if the annulment was just a civil annulment, or if it was a civil and Catholic annulment. The fact that Tom Joyce plays in a "gospel" band makes me think that he, at least, was/is not Catholic, since "gospel" isn't really a word that usually gets used as a descriptor for anything Catholic (other than "a reading from the Gospel of Whoever" during Mass). So it seems like it was probably a civil annulment only, probably filed for on grounds of "fraud" or "deceit" (by a partner who didn't intend to remain living with the family, not fraud or deceit because of the missing money issue).
ETA: If he did, in fact, seek an annulment. There's no proof of that, only a line on a discussion board by someone claiming inside knowledge. But all of that's hearsay.
*Note: Catholic, but not a lawyer