The 18-year-old Cambridge resident allegedly stabbed to death Saturday by a Harvard graduate student had a history of run-ins with the law, including a conviction on possession of crack cocaine with intent to distribute, court records show.

Michael D. Colono was allegedly stabbed outside of Pizza Ring early Saturday morning during an altercation with Alexander Pring-Wilson, a graduate student at Harvard’s Davis Center for Russian and Eurasian Studies. Pring-Wilson is now facing murder charges. His attorney says he will plead self-defense.

According to court records, both Colono and the two witnesses who were with him when the stabbing occurred—Samuel E. Rodriguez and Giselle E. Abreu—have criminal records.

Colono’s adult criminal record began with a Cambridge arrest in July 2001 for trespassing.

Two months later, Colono was arrested for possession of 16 small bags of crack cocaine with the intent to distribute as well as for the destruction of property.

He plead guilty to those charges and was given a two-year jail sentence—although the sentence was suspended for three years and never served.

Court records indicate that Colono was enrolled at a three-to-five-month residential alcohol treatment program at the Brighton Treatment Center

A clinic worker there wrote in December 2001 that she believed Colono was making substantial progress during his stay.

“Michael has identified long-term goals such as getting a job, taking classes at Bunker Hill Community College and providing a home for his daughter and girlfriend,” wrote substance abuse clinician Holly Boginski.

But in May 2002 Colono tested positive for opiates, according to court records.

Rodriguez, 21—who according to family was Colono’s cousin—spent six months in jail in 2001 for possession of a firearm without a license and resisting arrest. Rodriguez also admitted to possession of marijuana in 1999 and two incidents of assault and battery—including one with a dangerous weapon.

Nineteen-year-old Abreu, the other person accompanying Colono at the scene, was charged in March 2002 for driving a motor vehicle without a license. That charge was dismissed upon payment of court costs.

Rodriguez and Abreu could not be reached for comment yesterday.

Jeffrey Denner, Pring-Wilson’s attorney, said Colono and his companions’ history of arrests paint a different picture from the image his friends and family are trying to present.

“We have our own investigators out there,” Denner said. “This young man had numerous run-ins with the criminal justice system.”