However, relations between Bo and Wang became strained early this year, months after British businessman Neil Heywood, a family friend of Bo, was found dead in a Chongqing hotel room.
Wang, 52, fled to the US consulate and reportedly told officials that Bo's wife had killed Heywood.
On August 20, Gu was found guilty of murder and given a suspended death sentence.
The former right-hand man of ousted Chinese Politburo member Bo Xilai, Wang Lijun, has been tried in the southwestern Chinese city of Chengdu.
In his trial, which was held behind closed doors on Tuesday, Wang, the former police chief of the Chongqing municipality, faced charges of bribery, defection, abuse of power, bending the law for personal gain, and neglecting his duty of investigating and suppressing criminal acts.
The Chengdu Intermediate People's Court said after two half-day sessions that it would deliver its verdict later.
In February, Wang fled to the US consulate in Chengdu, creating a huge scandal, which led to the contentious dismissal of Bo in April, and the conviction of his wife, Gu Kailai, of the murder of a British businessman.
The party chief of Chongqing, Bo was widely seen as a candidate for a spot in the new leadership.
Wang was picked by Bo to organize a crackdown on the local mafia, which Bo hoped would get him promotion into the top ranks of the Communist Party.