Campbell then said that Copney told her prior to the Kirkland shooting that he had visited the home of a drug dealer named Justin Cosby. The two men smoked marijuana together and agreed to meet in Kirkland House—where Copney would buy 1.5 pounds of high-quality marijuana and 1.5 pounds of a lower-grade marijuana from Cosby, according to Campbell.

“Did he indicate what his intention was with regard to this marijuana?” Bennett asked.

“Yes, he was gonna rob him,” Campbell replied.

On the day of the shooting, Campbell said, “[Copney] told me that his boys were coming up from New York and that stuff was going down.... Bliz [Jiggetts] was coming up with a hammer.”

Campbell clarified that “a hammer” referred to a gun.

Campbell added, “He said he wasn’t afraid, and if Justin came back looking for him or if there were any problems, then he would air it out and put Harvard on the news.”

On cross-examination, Campbell acknowledged that she sold marijuana and cocaine during her time at Harvard. Amabile asked both Campbell and Bolton, based on their experiences as drug dealers, about the potential for a dispute during a drug transaction. Both dealers confirmed that buyers and sellers might argue over the quantity, quality, and price of marijuana exchanged—helping Amabile lay the grounds for one aspect of his defense.

With this testimony on the record, Amabile may later argue that, rather than entering the Kirkland annex with the intent of robbing Cosby, Copney was planning on exchanging money for drugs—a transaction which turned violent when Cosby’s product was not what Copney expected.

If the prosecution cannot convince the jury that the shooting occurred during the commission of a felony which is itself punishable by life in prison, such as armed robbery, then the jury has been instructed that it cannot find Copney guilty of first-degree murder.

Amabile pushed Campbell to name varieties of high-quality marijuana as he attempted to establish that quality can cause arguments during drug deals.

“I’ve been to Amsterdam three times.... I’ve been exposed to marijuana from all over the world,” said Campbell, who according to a 2008 Crimson article spent her junior year abroad, visiting 12 countries on three continents.

Bennett also asked Campbell about her drug use. She said she had smoked marijuana about 1,000 times, including daily use with Copney during her senior year, when Copney was living in Smith’s room in Lowell House.

—Kerry M. Flynn contributed reporting to this story.

—Staff writer Julie M. Zauzmer can be reached at jzauzmer@college.harvard.edu.