Around 2021-2022, the "Sandstone" building was completely renovated, removing the pool and expanding the building to integrate with the 2008 building, as well as removing the concrete beneath the concrete drive-up. All during this time, it was renamed as Christ Church (disconnect from the Methodist church over theology). The circa '99 building does not connect to the main combined building and still retains its covered walkways.
UPDATE 01-26-2025: A bit more on Desert Hills. It was a youth facility explicitly for troubled students (not those words). According to another article, "almost all of the students have abuse and/or neglect in their histories, officials said, and their behavior problems range from at-risk delinquent youths to moderately emotionally disturbed". Desert Hills was definitely still operational in 1996 (one caption was amended to account for this) as per this newspaper ad.
A 1998 article (when it was discussed of closing in September) mentions that placement was dictated by government entities (CPS and Juvenile Services). It worked closely with CSISD though it did receive an official charter to open as its own charter school before closing permanently. All this came down to money and politics. (Still, [school] has been added here).
CUMC bought the property in front of it in 1999 and built a small church with the address of 4203, the purchase of the former Desert Hills facility was in 2000, and that's when it adopted its current address.