The search is on for a software programmer at Yahoo who went missing without a trace New Year's Day.
Arduini has disappeared without telling anyone before, but the private investigator says Arduini--who's ominous last Instagram photo was of the Bay Bridge--has a history of emotional instability.
Arduini's social media feeds say very little about the man investigator James Vierra says sometimes has emotional outbursts.
'He talked about issues where he's be better off not being around,' claims Vierra.
Vierra declined to say who he's working for but KCBS reports that the missing man's friends are saying it's Yahoo.
Photos taken by host Dustin Diaz show him smiling with friends at a New Year's Eve party.
'We were having an awesome time,' Diaz told KCBS. 'We were laughing. A lot of the photos are of him just laughing.'
Friends say Arduini once went to Thailand alone without telling anyone, but that a week of total silence isn't normal even for him.
The last time Diaz saw Arduini, they were watching the New Year's fireworks over San Francisco.
From there, his only remaining traces are what lingers online.
A photo of the fireworks was posted to the programmer's Twitter with the phrase 'ITS THE FINALE.'
'To the various parties I've pissed off with my opinions and proselytizing in 2013: my apologies.
It's not getting any better in 2014,' he would later tweet.
On Instagram, Arduini's last photo was of the Bay Bridge. 'Bridge ing,' he wrote.
His final tweet said simply, 'Ok.'
And since January 1st the feeds have all gone silent.
Arduini left his cat unattended in his Oakland apartment and some reports have said that he's diabetic and left his insulin at home, as well.
He is 5-foot-10 and weighs between 150 and 170 pounds. He has brown hair and brown eyes. He has a tattoo of the number 42 on his neck and a tattoo of a heart with crossbones on his chest where there is also a tattoo of Linux code that reads 'rm –rf /.
Anyone with information is urged to contact Victor Arvizu of the Oakland police at (510) 238-3641.