Sullivan also said Jakubowski confessed to burglarizing the gun store in a previous court proceeding.
Jakubowski is charged with three felonies in Rock County in connection with the alleged burglary.
Tuesday's closing arguments followed a full day of court on Monday.
The prosecution called a total of three witnesses.
A Rock County Sheriff's detective walked jurors through surveillance video showing a man, who Detective Ronald Betley said was Jakubowski, breaking into and ransacking the gun store. The man is seen in the video yanking long guns off of a wall and clearing out handguns from a glass case.
The man in the video stashes the firearms into a duffle bag.
Betley added that Jakubowski "freely admitted" being in the gun store and seizing the weapons during an interview with investigators after he was taken into custody.
The gun store's owner also testified about the 18 guns, as well as silencers, ammunition, and magazines, that were missing from the building after it was burglarized last April.
Finally, a DNA analyst was called to the stand and said that, in his opinion, DNA recovered inside of the gun store belonged to Jakubowski.
After originally planning to testify in his own defense, Jakubowski refused to be sworn in on the stand, and the defense rested without calling a single witness.
"I will give (jurors) the truth but I will not raise my right hand," Jakubowski said from the witness stand.
"Then you will not testify," the judge replied.
Jakubowski's attorney walked up to the witness stand and whispered something in his ear.
But whatever was said did not change the defendant's mind.
"So he elects not to testify?" Judge James Daley asked.
"He does," replied Jakubowski's attorney.
This week's trial is Jakubowski's second in connection with the burglary at the gun store.
Late last year, he was found guilty in federal court and sentenced to 14 years in prison for stealing firearms and silencers from a federally-licensed dealer, as well as for being a felon in possession of firearms and silencers.