SEONGNAM, South Korea -- A former chief of staff to opposition leader Lee Jae-myung, who was found dead in an apparent suicide, urged the Democratic Party (DP) chair to quit politics in his suicide note, informed officials said Friday.

The deceased, surnamed Jeon, is also said to have complained about being investigated by prosecutors in connection with Lee's corruption allegations.

Jeon had served as Lee's chief secretary during his term as the mayor of Seongnam, just south of Seoul, before becoming his first chief of staff after Lee was elected governor of Gyeonggi Province in mid-2018.

Jeon was found dead at his home in Seongnam at 6:45 p.m. Thursday, and police said they have yet to find any sign of foul play in his death.

According to the officials, a six-page suicide note apparently written by Jeon was found on the scene. Jeon reportedly said in the note that he only worked hard but felt wronged after becoming a target of the prosecution's investigation.

Jeon was also quoted as telling Lee to leave politics, saying there should be no more sacrifices.

Jeon's family has refused to disclose the note, reportedly saying that he was stressed out as his name was mentioned in recent media reports on Lee's corruption allegations.

Indeed, Jeon was mentioned during a Jan. 31 court trial on former Gyeonggi Vice Gov. Lee Hwa-young, who is suspected of having received bribes from underwear maker Ssangbangwool Group and being involved in former Ssangbangwool Chairman Kim Seong-tae's foreign currency transfers to North Korea.

A former Ssangbangwool executive said as a witness during the trial at the Suwon District Court that in May 2019, the then Gyeonggi governor's chief of staff visited the mortuary of Kim's mother to offer condolences.

Jeon retired at the end of last year after serving as acting president of the Gyeonggi Housing & Urban Development Corp.

Before and after his retirement, Jeon was reportedly questioned by prosecutors in connection with allegations of Lee's third-party bribery surrounding corporate donations to football club Seongnam FC.

The case centers on the allegations that the city government of Seongnam attracted about 13.3 billion won (US$10 million) in donations from four entities to Seongnam FC in return for administrative favors in the mid-2010s, when Lee Jae-myung was serving as the city's mayor.

The DP leader blamed the prosecution for Jeon's death during a party meeting, saying that Jeon may have been under heavy pressure due to prosecutors' investigation and their creation of manipulated evidence.

But the prosecution said Jeon was questioned only once on Dec. 26 last year in connection with their investigation into the Seongnam FC case and a video recording was conducted at that time.

The prosecution said there was no additional questioning or summons for Jeon thereafter.

The police filed for an autopsy for more concrete circumstances about Jeon's death.

But prosecutors dismissed the request, citing probe results and opposition from the bereaved family.

Lee visited the funeral home set up at a hospital in Seongnam at around 8 p.m. with a grim face.

The scene was kept private from press while the DP leader paid his condolences to Jeon's family for about 20 minutes.

Lee remained silent to a flurry of questions from the media and left.

He was later quoted by DP spokesperson Han Min-soo as saying Jeon was "incredibly exemplary, the most earnest and able public officer that he had ever met, and (his death) breaks his heart."

Han also said Jeon's family "cheered Lee up and asked him to uncover the truth so that there will not be more unfair deaths."