Johnny Lewis -- String of Violent Crimes Before Alleged Murder

Johnny Lewis -- the "Sons of Anarchy" actor suspected of murdering his landlady Wednesday before falling off a roof to his death -- was convicted of several violent crimes in 2012 ... TMZ has learned.

According to official records, Lewis committed felony assault with a deadly weapon on January 3rd. The records don't specify the details of the crime, but they do show he was subsequently ordered to complete a rehab program for "treatment of mental health and/or drugs and alcohol."

The records also indicate Lewis was arrested on February 10th. Law enforcement sources tell us, he sucker-punched a man on his way out of a yogurt shop for no apparent reason.

Eight days afterwards, on February 18th, Lewis was arrested again for burglary. According to law enforcement sources, he had tried to break into a woman's house through a window, claiming he was looking for a friend ... but when the woman called cops, he took off.

Lewis was convicted of felony assault following his January arrest, and sentenced to a year in county jail. Lewis was also convicted of battery and burglary following his February arrests, and sentenced to 303 days in jail for those two crimes.

It's unclear exactly how many days he served and whether he spent the majority of his time in jail or in rehab. Lewis was ultimately released from jail SIX DAYS AGO on September 21st.