Andrus was released from custody at about 9:30 p.m. Tuesday night.
District attorney's office spokesman Alex Bastian said Tuesday afternoon that prosecutors were "very disturbed" by the facts of the case, but "given the current state of the evidence, there is insufficient evidence to charge this suspect with murder."
Andrus was detained Friday afternoon after being identified as a person of interest in the case and was booked into jail early Saturday on suspicion of murder.
The statement went on to say, "Until we have the evidence necessary to prove this case beyond a reasonable doubt, we are ethically obligated to hold off on charging this suspect."
Public Defender Jeff Adachi, whose office planned to represent Andrus, said "we are relieved" to find out he is not being charged.
Adachi said late Tuesday afternoon that he was headed to the jail to notify Andrus of the district attorney's decision.
Additional remains were found in a trash can half a block away from the initial crime scene Wednesday and police said some body parts remained missing.
A source close to the investigation earlier Tuesday confirmed to KTVU San Francisco police are trying to determine whether the decapitated and handless body found Wednesday in a suitcase and a trash can is that of 58-year-old Vallejo resident Omar Shahwan.
Mark Keever, a friend of Andrus, said the two met a couple of years ago.
"I met him on the streets," Keever said. "He's a nice guy. He treated me like a friend."
Keever believes Andrus is innocent. "That's not him," he added. "He wasn't the one."
Multiple sources stated the two were friends, but for now Andrus is a free man who Adachi says will be around to face any future charges.
"They haven't indicated that they want him to report or they're going to be monitoring him in any way," said Adachi. "He has no plans to leave San Francisco, so he'll be here."
Adachi said he would make sure his client had a placed to stay Tuesday night.