 Complete the following phrase:  The involvement of Pablo Escobar in the club remained strong. Some referees were threatened in the league and even in the Copa Libertadores, for which CONMEBOL banned Colombian clubs from the 1990 Copa Libertadores, with the exception of Nacional who was admitted as champion of the previous edition. However, the team had to play its home matches in Chile. In 1989, the domestic league season was cancelled due to the assassination of referee Álvaro Ortega on 1 October. In October, the team played the Supercopa Libertadores and were eliminated in the quarterfinals by Independiente. On 17 December, Nacional played the 