Suspected gunman Robert Lewis Dear Jr. is in custody after a shooting at a Planned Parenthood clinic in Colorado left three people dead, including one police officer. Here's what else we know about the victims, the suspect and the incident. (The Washington Post)

The shootings at a Planned Parenthood facility in Colorado Springs, Colo., over the holiday have put the debate over the women's health services and abortion provider back in the news. And already, left and right are arguing in very heated terms over the shooter reportedly saying "no more baby parts" while discussing his motives.

Republicans dismiss the role of antiabortion rights rhetoric in the attack, while those on the left argue that this is the result of such talk. But what's undeniable is that both sides have spent the past several months arguing over abortion in increasingly pitched terms.

The perennially divisive issue seized the national spotlight in July when an antiabortion advocacy group released undercover videos of Planned Parenthood officials talking about fetal tissue donations.

The fallout has threatened to shut down the government, take away hundreds of millions in federal funding from Planned Parenthood and has already become a major campaign issue, expanding into a debate on gun control and domestic terrorism.

Here are six of the debate's most heated moments, in chronological order:

1. July: The first video drops
The anti-abortion group Center for Medical Progress posted a long version of the conversation between a Planned Parenthood executive and undercover actors on YouTube along with an shorter version that has been shared widely. These are excerpts of the longer version. (CenterforMedicalProgress.org)

The antiabortion group Center for Medical Progress releases an undercover video that they say shows Planned Parenthood officials trying to sell fetal tissue, discussing practices for extracting organs over glasses of wine and salad.

GOP presidential candidates immediately call it "shocking," "tragic," "horrific" and "outrageous."

Planned Parenthood officials apologize for their cavalier tones in the video but maintain that they did nothing wrong (selling fetal tissue for profit is illegal in America, but donating tissue and accepting payments to recoup those costs is legal.). In an interview with ABC News, Planned Parenthood President Cecile Richards calls the group that recorded the videos "militant."

"The folks behind this are part of the most militant wing of the antiabortion movement that has been behind the bombing of clinics, the murder of doctors in their homes and in their churches.

2. August: The movement to defund Planned Parenthood begins

Senate Republicans move first, part of a series of votes Congress will take over the summer and fall to strip Planned Parenthood of some $500 million a year in public funds (which is not legally allowed to go to pay for abortions).

[Meet the three GOP women leading the charge to defund Planned Parenthood]

But Senate Democrats block the bill, incensed that the nonprofit women's health-care clinic is even an issue being debated.

The legislation was "just one more piece of a deliberate, methodical, orchestrated, right-wing attack on women's rights. And I'm sick and tired of it," Sen. Elizabeth Warren (D-Mass.) says after the vote, according to Reuters. "... I want to say to my Republican colleagues, the year is 2015, not 1955 and not 1895."

3. September: Congressional hearings on Planned Parenthood get dramatic

Republican leaders in Congress move to set up no fewer than four separate probes into various aspects of the Planned Parenthood controversy.

One of the first begins Sept. 9 in the House Judiciary Committee. Titled "Planned Parenthood Exposed: Examining the Horrific Abortion Practices at the Nation’s Largest Abortion Provider," Republican committee leaders invite four witnesses, three of whom are abortion-rights foes and two of whom say they survived their mothers' abortions.

The Washington Post's Sandhya Somashekhar reports that the hearing focused less on the specific ins and outs of Planned Parenthood's fetal tissue donation program and more on the age-old questions of when life begins.

Lawmakers and witnesses debated the perennial term "baby" versus "pre-viable fetus" and abortion techniques. Witness Gianna Jessen talks about her mother's abortion that she said nearly killed her:

"I have long believed if my birth mother’s abortion had taken place at a Planned Parenthood,” she testifies, “I would not be here today.”

4. September: Planned Parenthood's leader comes to Congress
Planned Parenthood president Cecile Richards appeared before the House Committee on Oversight and Government Reform to defend the organization against allegations of illegally selling fetus tissues for profit. Things quickly became heated between Richards and several lawmakers. (Alice Li/The Washington Post)

Richards's hours-long testimony in front of the House Oversight and Government Reform committee, headed by vocal abortion foe Rep. Jason Chaffetz (R-Utah), quickly becomes a flashpoint in the debate.

Chaffetz starts off trying to pinpoint how much money Richards makes, seriously upsetting Democrats in the room like Rep. Carol Maloney (D-N.Y.), who says: "In my entire time I've been in Congress, I've never seen a witness beaten up and questioned about their salary. I find it totally inappropriate and discriminatory."

Then, Rep. Jimmy Duncan (R-Tenn.) wants to know whether Richards defends the sale of fetal tissue. When he isn't satisfied with her answer, he essentially compares her to a criminal, saying: "It seems to me that the apology you offered was like what some criminals do. They're not really sorry for what they have done."

[The 5 most contentious exchanges from Congress's Planned Parenthood hearing]

5. September: Carly Fiorina says videos show 'fully formed fetus'
The second debate for top Republican presidential candidates included bashing Donald Trump, a fiery Carly Fiorina and an admission from Jeb Bush that he says his mom won't like. (CNN)

It was a moment that struck a cord with antiabortion conservatives. But when former Hewlett-Packard CEO and GOP presidential hopeful Carly Fiorina describes the undercover Planned Parenthood videos this way at September's GOP presidential debate — "Watch a fully formed fetus on the table, its heart beating, its legs kicking while someone says we have to keep it alive to harvest its brain" — fact-checkers point out no such clip exists in the Planned Parenthood videos.

[What is actually in the undercover Planned Parenthood videos]

Planned Parenthood tries in vain to ask Fiorina for a retraction, but she doubles down instead.

Three days after the debate, her super PAC puts together a video featuring her emotional appeal at the debate. Her campaign defiantly issues this statement: "Planned Parenthood doesn't and can't deny they are butchering babies and selling their organs.”

6. October: The investigations in Congress continue

The federal government ended up not getting shut down over a debate about Planned Parenthood — thanks in no small part to former House speaker John Boehner's (R-Ohio) sudden resignation.

But that doesn't mean that the issue is off the table. A few days after Boehner's last day, House Republicans vote to create a special committee to investigate the practices of abortion and fetal tissue procurement.

The committee of eight Republicans and five Democrats has broad power to subpoena — not unlike Republicans' committees to investigate the 2012 attacks in Benghazi, Libya.

Democrats and Planned Parenthood officials are not happy that Republicans are focusing on abortion in such detail. A Planned Parenthood official calls the new committee "part of a political agenda to make abortion illegal," and in an interview with The Post's Mike DeBonis, Rep. Xavier Becerra (D-Calif.) compares the committee to the 1950s investigations in Congress of communism:

“We may be going back to some of those bad old days."