BERLIN (Reuters) - The German government said on Monday nobody should try to make political capital out of a criminal case involving an Afghan refugee suspected of raping and murdering a German university student.

The case could bolster support for anti-immigrant groups such as the Alternative for Germany (AfD), which have already gained ground after Germany admitted nearly a million mostly Muslim migrants and refugees last year.

Last Friday police detained a 17-year-old Afghan schoolboy who arrived in Germany last year and a test determined that his DNA matched that found near the site where a 19-year-old female student died in the southwestern city of Freiburg on Oct. 15.

Police said an autopsy found she had been a victim of sexual crime and violence before she drowned in a river.

“We must not allow this abominable crime to be misused for rabble-rousing and conspiracy propaganda,” German Vice Chancellor Sigmar Gabriel said on Facebook.

Government spokesman Steffen Seibert said the Afghan refugee “must be punished with the full force of our laws” if found guilty.

“But we must not forget that we are talking then about a possible crime by one Afghan refugee, not a whole group of people who are Afghan or refugees,” Seibert added.

Their comments reflect the political sensitivity of crimes involving migrants after Chancellor Angela Merkel’s open-door policy triggered a sharp fall in her popularity. She wants to seek a fourth term in next year’s federal election in Germany.

Some Germans also suspect their government and mainstream media of trying to hush up incidents involving migrants to avoid a political backlash.

When hundreds of women were sexually assaulted and robbed by men of North African and Arab appearance during New Year celebrations in Cologne on Dec. 31, national news outlets did not report them until several days later, prompting strong criticism from anti-immigrant groups.

German public broadcaster ARD came under fire on social media for not including a report in its Saturday night news broadcast on the case involving the Afghan migrant suspect, with some accusing it of being too politically correct.

ARD Chief Editor Kai Gniffke defended the decision, saying in a blog that journalists were not “emotionless” but ARD seldom reported on individual crime cases and chose instead to focus on “events of social, national and international relevance”.