Updated

Jurors convicted white Chicago police Officer Jason Van Dyke for murder and aggravated battery in the slaying Laquan McDonald, the black teenager who was shot 16 times as he walked away carrying a knife on Oct. 20, 2014.

But a legal expert explained that the 40-year-old Van Dyke is likely looking at less than 10 years in prison for killing the teen rather than many decades because jurors opted to convict him of second- and not first-degree murder.

Here is a look at the convictions and how much time Van Dyke may end up of spending behind bars:

CONVICTION

After less than two full days deliberating on three weeks of testimony, jurors returned Friday with 17 guilty verdicts and one acquittal. By far the most serious charge Van Dyke faced originally was first-degree murder.

But Judge Vincent Gaughan told jurors before they started deliberations that they had the option of replacing first-degree murder with second-degree murder.

First-degree required a finding that Van Dyke's use of deadly force wasn't justified — that it was both unnecessary and unreasonable. But Gaughan said jurors could find that Van Dyke truly believed his life was in jeopardy but that that belief wasn't reasonable. That's the criteria for second-degree murder.

The jury also found Van Dyke guilty of all 16 counts of aggravated battery with a firearm. Each count corresponded to every bullet Van Dyke shot into McDonald.

They acquitted him on the least serious charge, official misconduct.

SENTENCE

Van Dyke showed little emotion as the verdicts were read out in court. He may have had reason for feeling some relief.

First-degree murder carries a maximum sentence of life imprisonment. And with enhancements for having used a gun, Van Dyke would have faced a mandatory minimum of 45 years, according to Chicago defense attorney Steve Greenberg, who has defended clients at more than 100 murder trials. Such a sentence, at Van Dyke's age, could have amounted to life.

The punishment for second-degree murder is no less than four years but no more than 20 years behind bars.

Jurors weren't told anything about the range of punishments for each charge. The judge did tell them that whether one charge might carry a greater or lesser sentence shouldn't factor at all into their decisions.

Each count of aggravated battery carries a mandatory minimum six years and a maximum of 30 years in prison. If Van Dyke had to serve six for each of the 16 counts — and do so one sentence after another — that would add up to 96 years. But Greenberg said judges almost always order defendants to serve such sentences simultaneously. So, if Van Dyke gets the minimum for each count, he'd serve six years for all the battery convictions.

Another possibility is that the defense will ask, under complicated legal rules, for the judge to merge the crimes for which Van Dyke is convicted for sentencing purposes since they were all tied to a single event, Greenberg said. That could mean Van Dyke is effectively sentenced only for second-degree murder, with its lower four-year mandatory minimum.

For a man convicted with no previous criminal record, Greenberg said the mandatory minimum is his best guess for a sentence handed down on Van Dyke.

"I would be shocked if he got a day over the four or six years," Greenberg said.

PRISON CONDITIONS

Greenberg said prison conditions for an officer, like Van Dyke, could be rougher than for average convicts. As a white officer convicted of killing a young African-American, prison authorities are likely to conclude he has to be kept away from other prisoners for his own safety.

"He will probably be in a cell by himself," Greenberg said. "It will be very hard time."

That may have already started.

At prosecutors' request, Van Dyke's bond was revoked minutes after the verdicts were announced and Judge Gaughan ordered he be held in jail pending sentencing. He stood up from the defense table, then put his arms behind his back as two deputies led him away.

___

Follow Michael Tarm on Twitter at http://twitter.com/mtarm

For the AP's complete coverage of the case: https://apnews.com/tag/LaquanMcDonald