SEOUL: South Korea's investigators called off their attempt to arrest impeached President Yoon Suk Yeol at his residence Friday over a failed martial law bid, citing safety concerns after a standoff with his security team. Yoon, who has already been suspended from duty by lawmakers, would become the first sitting president in South Korean history to be arrested if the warrant is carried out. The president, who issued a bungled declaration on December 3 that shook the vibrant East Asian democracy and briefly lurched it back to the dark days of military rule, faces imprisonment or, at worst, the death penalty. "Regarding the execution of the arrest warrant today, it was determined that the execution was effectively impossible due to the ongoing standoff," the Corruption Investigation Office (CIO), which is probing Yoon over his martial law decree, said in a statement. "Concern for the safety of personnel on-site led to the decision to halt" the arrest attempt, the statement said of the confrontation with Yoon's presidential security service and its military unit. The deadline for the warrant is Monday, leaving it in limbo with just a few days remaining and Yoon defiant, vowing earlier this week to "fight" authorities seeking to question him. CIO investigators including senior prosecutor Lee Dae-hwan were earlier let through heavy security barricades to enter the residence to attempt to execute their warrant to detain Yoon. But soldiers under the Presidential Security Service at one point engaged in a "confrontation with the CIO at the presidential residence," an official with Seoul's Joint Chiefs of Staff told . Before the execution of the court-approved warrant was called off, Yoon's security detail told they had been "in negotiation" with the CIO investigators who sought to access the president. Yoon's security service — which still protects Yoon as the country's sitting head of state — has previously blocked attempted police raids of the presidential office. The president himself has ignored three rounds of summons from investigators, prompting them to seek the warrant. Yoon's legal team — who raced to the residence and saw allowed inside — decried the attempt to execute the arrest warrant, vowing to take further legal action against the move. "The execution of a warrant that is illegal and invalid is indeed not lawful," Yoon's lawyer Yoon Kap-keun said. On Friday, prosecutors also indicted two top military officials including one who was briefly named martial law commander during last month's fiasco, on charges of insurrection, reported. Both were already in detention. Dozens of police buses and hundreds of uniformed police lined the street outside the compound in central Seoul, reporters saw. About 2,700 police and 135 police buses were deployed to the area to prevent clashes, reported, after Yoon's supporters faced off with anti-Yoon demonstrators Thursday.