He was handcuffed. Kyari was handcuffed and arrested like any other suspect,and will be handed over to the appropriate agency. He was not given any preferential treatment.

NDLEA spokesperson, Femi Babafemi, had at a press briefing in Abuja on Monday, chronicled how Kyari belonged to a drug cartel that operates the Brazil-Ethiopia-Nigeria illicit drug pipeline.
The anti-drug agency said Kyari contacted one of its officers in Abuja and struck a deal to secure the release of a total of 25kg seized cocaine.

Babafemi said, “After the Agency gave the officer the green light to play along, he and Kyari began a WhatsApp call for the rest of the day. The officer conveyed “their” willingness to play the game.”
“He (Kyari) brought with him the money from the sale of the 5kg share of the NDLEA team, a total of $61, 400. Our officer, however, preferred to take the money inside his car. Well, the car was wired with sound and video recorders. And the moment was documented, part of which I will play for you at the end of this briefing.
“We have a trove of intelligence, hard facts, from chats to photos and video and a detailed transcript of the communication between him and the NDLEA officer,” NDLEA spokesperson said.