NASHVILLE, Tenn. -- Police said Friday night they have charged three men and a woman for their alleged involvement in the shooting death of a Vanderbilt professor this week in east Nashville.

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Professor Pierre Colas, 32, was found dead and his sister, Marie Colas, 27, was wounded from shots to the head on Tuesday night in east Nashville.

Those charged are Thomas Andrew Reed, 20; Michael Shane Holloway, 22; George Eugene Cody, 29; and Gennyfer Dawn Hutcherson, 35. Holloway and Reed are brothers from Cookeville, while Cody and Hutcherson live near where the shooting occurred.

Three of the men were taken by police for questioning at 7 a.m. Friday.

According to detectives, Pierre Colas' credit card was recently used at several businesses. Police said there is surveillance video that shows the individuals using the card.

The three men had been seen driving a gold 1992 Buick Regal. On Thursday night, police saw that car with all three men inside and followed it to 891 Sharpe Avenue.

"We are in the process right now of interviewing those individuals. We have a car of interest ... (that we will process). We also have a residence of interest that we are going to do the same with. We're waiting to obtain search warrants," said Lt. Danny Driskell of the Metro Police Department.

Police said they are were also searching a Nashville La Quinta Inn on Sidco Drive where a couple of the men recently stayed.

Police said on Thursday that during their investigation they were looking at a variety of circumstances that could have led to the death of the anthropology professor.

"This gentleman was well-liked as an educator, who was looked up as a mentor by his students," said Driskell.

There was no forced entry into the home, and police said it is possible he was accosted while he was on his front porch and forced back inside his home on McFerrin Avenue in east Nashville.

"We know just from what neighbors have said that he was last seen on his porch about 15 to 20 minutes before the 911 call came in that he had been shot. We don't know if he was actually confronted by the suspect on the front porch and forced back into his house, or if he had actually gone back into his house and perhaps the door was left unlocked, or if he just left it open intending to return to the porch and was confronted by the suspect inside his residence," said Detective Matt Filter of Metro Police.

Marie Colas was visiting her brother from Switzerland and has been in town for about a week. She is at Vanderbilt Medical Center with critical injuries.

Residents of the neighborhood where the shooting occurred held a candlelight vigil this weekend in Colas' honor.