If you take notice of some photos youll see different portable types in use. Some use the VRS, some do not. Some use VHF HT1000s on 155.550 as it is also NMSP T/A and dispatch does reply on it for the ones who do not have or use the VRS UHF. Keep in mind not every transmission is on the duplex dispatch may call on the duplex VHF but officers may chooseto reply back on the state car, NMSP F4, or other channel. The scan lists for the NMSP radio is at the default drop. Why most of the time youll hear them say 834 to Mary 233 on vlaw32, state car, local, etc. so they know what channel to reply on. The newer setups are connected to the MDT and it will allow the channels to be replied on and displays what your on or what last channel the audio came in on. Even if NMSP was to go to a DVRS 700mhz it would be like the past where half the fleet is using the DVRS 700mhz while the rest are still UHF VRS. Gotta love budget crunching. Here is photos showing the different handhelds some have.
Google Image Result for http://www.timkellerphotography.com/timkellerarts/Images/MCIdrillEMS/NMSP.jpg
Google Image Result for http://2.bp.blogspot.com/_VMFVYmhIKYA/TNA4tQ7yNAI/AAAAAAAAAFk/2bHfEFXxvKA/s1600/10:10:31-NMSP-PSA_1534w.jpg
Google Image Result for http://www.nmmtdpolice.org/wp-content/uploads/2011/03/MVC-016S.jpg
If you do other searches it will show various hand helds used depending on what district it is.
I found one thing in the first picture. The officer looks like he is wearing a wildland firefighter/forester type boot, which typically have the under slung heal portion of the sole.
The third picture shows a different colored car and the officer wearing a "Smokey" hat. Additionally there isn't a side stripe on his pants. I can't quite see the shoulder patch but it looks different than the white triangle patch of the state police. Could this be a Motor Transportation Police officer?
I don't recall the Motor Transportation Police when I lived in New Mexico in the late 70's and early 80's. They may have existed then, but without the Internet information was more difficult to come by and I probably never saw one of their units on the highway. What radio system do they use? Do they use the NMSP system or do they have one of their own?