In November, a federal judge granted a US government request to drop drug charges against Cienfuegos and return him to Mexico, which called it a move that would restore trust in the neighbors' severely strained security ties.
Lawmakers last month amended Mexico's security law to restrict the work of foreign agents on Mexican soil despite fierce opposition from Washington.
The new rules published on Thursday detail the mechanisms that will govern how foreign agents would have to work with local Mexican government counterparts.
The new daily death toll marks the fifth consecutive day that officials have reported more than 1,000 fatalities due to the highly contagious disease caused by the virus.
The coronavirus pandemic had an unprecedented impact on the global economy, thrusting economies into uncharted territory - and drug cartels were no different.
The cartel - being one of the world's most powerful drug trafficking groups - used a mix of ingenuity and business acumen to adapt to the rapidly changing circumstances in a pandemic-stricken world.
Leftist leader Lopez Obrador, who has vowed to prioritize the poor in a country with huge wealth disparity, has said the previous minimum salaries were shameful.
Janssen has begun its coronavirus clinical trials in Mexico, and Lopez-Gatell said the memorandum his government signed on Monday gave it the option of ordering additional doses.