Courageous

When his truck is stolen at a Gas Station, Nathan Hayes chases it and manages to apprehend the driver and reclaim the truck. Though he is injured, he crawls back to the car, and sees that his little baby boy in the back is okay. When the police arrive, Adam Mitchell and Shane Fuller meet Hayes, discovering he is a new deputy, having recently moved.
The personal lives of these officers are observed: Mitchell adores his nine-year-old daughter, Emily, but is distant from his fifteen-year-old son, Dylan, because Mitchell doesn't share Dylan's interest in 5k runs. Hayes never knew his biological father, instead treating a neighbor as his father (even giving him Father's Day cards annually), but would risk his life to save his three children; however, his teenage daughter Jade (Taylor Hutcherson), resents him because he has a strict policy about dating. Fuller is divorced, as were his parents, and has joint custody of his son. Thomson is young and single.
Javier Martinez (Robert Amaya), an immigrant struggling to provide for his family, is walking down an alley asking God what He wants him to do after being laid off when a construction company went over budget and Mitchell calls him over to help with his shed, thinking he is a different Javier that Mitchell's friends said would help him. After paying him for the job, Mitchell recommends him to a new full-time job, where he is hired.
One day, Emily is killed by a drunk driver, devastating Mitchell and his family. Following his daughter's death, Mitchell reads a lot about fatherhood in the Bible. He decides he must be a better father and crafts a detailed "Resolution" to honor God in every aspect of his family. Mitchell, Hayes, Fuller, Thomson, and Martinez join him in his resolution at a formal ceremony conducted by Hayes's neighborhood mentor, the man he thinks of as a father. As a result of the resolution, Mitchell and Fuller mend their relationships with their sons, Hayes with his daughter, and he also visits the grave of his biological father who he had never met and forgives him. Thomson reveals that he fathered a child in college and deserted the mother after she refused to have an abortion. He writes the mother and seeks to mend their relationship and to see his child, after seeing that abandoning kids is what creates the crimes on the streets, and does not want that on her.
Martinez's manager offers him a promotion on the condition that he falsify inventory documents. After being given a day to think about it, Martinez refuses, acknowledging it would be wrong. Impressed, his boss promotes Martinez and raises his pay when he reveals that the condition was a test of Javier's integrity, with him being the only one to pass after many have been tested.
Mitchell discovers that Fuller has been stealing drugs from police evidence to resell on the streets for the money. Mitchell decides he must honor his Resolution and report the corruption. He sets up a sting leading to Fuller's arrest and imprisonment. Fuller explains his motives that he was doing it for his son, feeling that his yearly pay wasn't enough to provide for him. Mitchell visits Fuller in jail where Fuller admits to his mistakes and asks Mitchell to look after his son. During a minor traffic stop, Hayes and Thomson unknowingly confront the armed leader of a gang they have been repeatedly encountering. One of the gang members is Derrick, who stops the gang leader from shooting Hayes with a shotgun. After an intense fallout, Deputy Hayes asks Derrick, a boy who wanted to date Jade with Hayes refusing it, what he's doing with the gang, and he responds that he had no one else that cared about him.
At a Father's Day church service, the men present the Resolution and Mitchell urges the fathers in the congregation to be a Godly influence on their families. Mitchell runs in a 5K race with his son and Fuller's son, Hayes biblically influences Derrick in prison, and Thomson meets his daughter for the first time.

Question: What has Fuller been stealing?
Answer: drugs